feat: 分类系统 + 标签系统 — Phase 4 完成

分类：Model/Repo/Service/Controller + 管理后台树形页面 + 首页导航栏
标签：Model/Repo/Service/Controller + /tags/{slug} 落地页 + 写文章页输入
Post 加 CategoryID，Create/Update 支持分类和标签
SQL 迁移含 categories/tags/post_tags 表及预设未分类

templates/admin/html/categories/index.html

@@ -0,0 +1,80 @@
+{{template "admin/layout/base.html" .}}
+        <div class="page-header">
+            <h1>分类管理</h1>
+            <p class="page-desc">两级树形分类，仅叶子节点可被文章选择</p>
+        </div>
+
+        <div class="toolbar">
+            <button class="btn btn-primary" id="btnNewCategory">+ 新建主分类</button>
+        </div>
+
+        <div id="categoryTree" class="category-tree">
+            {{range .Tree}}
+            <div class="cat-node cat-parent">
+                <div class="cat-row">
+                    <span class="cat-name">{{.Name}}</span>
+                    <span class="cat-slug">/{{.Slug}}</span>
+                    <span class="cat-actions">
+                        <a href="#" class="cat-btn-edit" data-id="{{.ID}}" data-name="{{.Name}}" data-slug="{{.Slug}}" data-desc="{{.Description}}" data-sort="{{.Sort}}">编辑</a>
+                        <a href="#" class="cat-btn-delete" data-id="{{.ID}}">删除</a>
+                        <a href="#" class="cat-btn-add-child" data-parent-id="{{.ID}}">+ 子分类</a>
+                    </span>
+                </div>
+                {{if .Children}}
+                <div class="cat-children">
+                    {{range .Children}}
+                    <div class="cat-row cat-child">
+                        <span class="cat-name">{{.Name}}</span>
+                        <span class="cat-slug">/{{$.Slug}}/{{.Slug}}</span>
+                        <span class="cat-actions">
+                            <a href="#" class="cat-btn-edit" data-id="{{.ID}}" data-name="{{.Name}}" data-slug="{{.Slug}}" data-desc="{{.Description}}" data-sort="{{.Sort}}" data-parent-id="{{.ParentID}}">编辑</a>
+                            <a href="#" class="cat-btn-delete" data-id="{{.ID}}">删除</a>
+                        </span>
+                    </div>
+                    {{end}}
+                </div>
+                {{end}}
+            </div>
+            {{else}}
+            <div class="cat-empty">暂无分类</div>
+            {{end}}
+        </div>
+
+        <!-- 编辑弹窗 -->
+        <div class="modal-overlay" id="modalOverlay">
+            <div class="modal">
+                <div class="modal-header">
+                    <h3 id="modalTitle">新建分类</h3>
+                    <button class="modal-close" id="modalClose">&times;</button>
+                </div>
+                <div class="modal-body">
+                    <form id="categoryForm">
+                        <input type="hidden" id="catId">
+                        <input type="hidden" id="catParentId">
+                        <div class="form-group">
+                            <label for="catName">名称</label>
+                            <input type="text" id="catName" class="form-input" maxlength="50" required>
+                        </div>
+                        <div class="form-group">
+                            <label for="catSlug">Slug（URL 标识）</label>
+                            <input type="text" id="catSlug" class="form-input" maxlength="50" pattern="[a-z0-9\-]+">
+                        </div>
+                        <div class="form-group">
+                            <label for="catDesc">简介</label>
+                            <input type="text" id="catDesc" class="form-input" maxlength="200">
+                        </div>
+                        <div class="form-group">
+                            <label for="catSort">排序</label>
+                            <input type="number" id="catSort" class="form-input" value="0" min="0" style="width:100px">
+                        </div>
+                    </form>
+                </div>
+                <div class="modal-footer">
+                    <button class="btn btn-secondary" id="modalCancel">取消</button>
+                    <button class="btn btn-primary" id="modalSave">保存</button>
+                </div>
+            </div>
+        </div>
+
+        <div class="toast" id="toast"></div>
+{{template "admin/layout/footer.html" .}}

templates/admin/html/layout/base.html

@@ -55,6 +55,10 @@
                 <span class="sidebar-icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M12 1v4M12 19v4M4.22 4.22l2.83 2.83M16.95 16.95l2.83 2.83M1 12h4M19 12h4M4.22 19.78l2.83-2.83M16.95 7.05l2.83-2.83"/></svg></span>
                 公户流水
             </a>
+            <a href="/admin/categories" class="sidebar-item {{if eq .CurrentPath "/admin/categories"}}active{{end}}">
+                <span class="sidebar-icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M3 3h7v7H3V3z"/><path d="M14 3h7v7h-7V3z"/><path d="M3 14h7v7H3v-7z"/><path d="M14 14h7v7h-7v-7z"/></svg></span>
+                分类管理
+            </a>
             <a href="/admin/announcements" class="sidebar-item {{if eq .CurrentPath "/admin/announcements"}}active{{end}}">
                 <span class="sidebar-icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M18 8A6 6 0 0 0 6 8c0 7-3 9-3 9h18s-3-2-3-9"/><path d="M13.73 21a2 2 0 0 1-3.46 0"/></svg></span>
                 公告管理

templates/admin/static/css/categories.css

@@ -0,0 +1,18 @@
+/* Categories Admin */
+.category-tree { margin-top: 16px; }
+.cat-node { margin-bottom: 12px; }
+.cat-parent { background: #f9fafb; border: 1px solid #e5e7eb; border-radius: 8px; padding: 12px 16px; }
+.cat-children { margin-left: 24px; margin-top: 8px; }
+.cat-row {
+    display: flex; align-items: center; gap: 12px;
+    padding: 8px 0; border-bottom: 1px solid #f3f4f6;
+}
+.cat-children .cat-row:last-child { border-bottom: none; }
+.cat-name { font-weight: 600; font-size: 14px; color: #111827; min-width: 80px; }
+.cat-slug { font-size: 12px; color: #9ca3af; }
+.cat-actions { margin-left: auto; display: flex; gap: 8px; font-size: 13px; }
+.cat-actions a { color: #3b82f6; text-decoration: none; }
+.cat-actions a:hover { text-decoration: underline; }
+.cat-btn-delete { color: #ef4444 !important; }
+.cat-btn-add-child { color: #22c55e !important; }
+.cat-empty { text-align: center; color: #9ca3af; padding: 40px 0; }

templates/admin/static/js/categories.js

@@ -0,0 +1,118 @@
+(function () {
+    'use strict';
+
+    var modalOverlay = document.getElementById('modalOverlay');
+    var modalTitle = document.getElementById('modalTitle');
+    var modalClose = document.getElementById('modalClose');
+    var modalCancel = document.getElementById('modalCancel');
+    var modalSave = document.getElementById('modalSave');
+    var catId = document.getElementById('catId');
+    var catParentId = document.getElementById('catParentId');
+    var catName = document.getElementById('catName');
+    var catSlug = document.getElementById('catSlug');
+    var catDesc = document.getElementById('catDesc');
+    var catSort = document.getElementById('catSort');
+    var toast = document.getElementById('toast');
+
+    function showToast(msg, isError) {
+        toast.textContent = msg;
+        toast.className = 'toast' + (isError ? ' toast-error' : ' toast-success');
+        toast.style.display = 'block';
+        setTimeout(function () { toast.style.display = 'none'; }, 2500);
+    }
+
+    function closeModal() { modalOverlay.classList.remove('active'); }
+    modalClose.addEventListener('click', closeModal);
+    modalCancel.addEventListener('click', closeModal);
+    modalOverlay.addEventListener('click', function (e) { if (e.target === modalOverlay) closeModal(); });
+
+    function openModal(data) {
+        if (data) {
+            modalTitle.textContent = '编辑分类';
+            catId.value = data.id || '';
+            catParentId.value = data.parentId || '';
+            catName.value = data.name || '';
+            catSlug.value = data.slug || '';
+            catDesc.value = data.desc || '';
+            catSort.value = data.sort || 0;
+        } else {
+            modalTitle.textContent = '新建分类';
+            catId.value = '';
+            // Keep parentId for child categories
+            catName.value = '';
+            catSlug.value = '';
+            catDesc.value = '';
+            catSort.value = 0;
+        }
+        modalOverlay.classList.add('active');
+    }
+
+    document.getElementById('btnNewCategory').addEventListener('click', function () {
+        catParentId.value = '';
+        openModal(null);
+    });
+
+    document.addEventListener('click', function (e) {
+        if (e.target.classList.contains('cat-btn-add-child')) {
+            e.preventDefault();
+            catParentId.value = e.target.getAttribute('data-parent-id');
+            openModal(null);
+        }
+        if (e.target.classList.contains('cat-btn-edit')) {
+            e.preventDefault();
+            openModal({
+                id: e.target.getAttribute('data-id'),
+                parentId: e.target.getAttribute('data-parent-id') || '',
+                name: e.target.getAttribute('data-name'),
+                slug: e.target.getAttribute('data-slug'),
+                desc: e.target.getAttribute('data-desc'),
+                sort: e.target.getAttribute('data-sort'),
+            });
+        }
+        if (e.target.classList.contains('cat-btn-delete')) {
+            e.preventDefault();
+            var id = e.target.getAttribute('data-id');
+            if (!confirm('确定删除此分类？')) return;
+            fetch('/api/admin/categories/' + id, { method: 'DELETE' })
+                .then(function (r) { return r.json(); })
+                .then(function (resp) {
+                    showToast(resp.message || '已删除', !resp.success);
+                    if (resp.success) window.location.reload();
+                });
+        }
+    });
+
+    modalSave.addEventListener('click', function () {
+        var data = {
+            name: catName.value.trim(),
+            slug: catSlug.value.trim() || slugify(catName.value.trim()),
+            description: catDesc.value.trim(),
+            sort: parseInt(catSort.value) || 0,
+        };
+        var pid = catParentId.value;
+        if (pid) data.parent_id = parseInt(pid);
+
+        if (!data.name) { showToast('请输入名称', true); return; }
+
+        var url = '/api/admin/categories';
+        var method = 'POST';
+        var id = catId.value;
+        if (id) { url += '/' + id; method = 'PUT'; }
+
+        fetch(url, {
+            method: method,
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify(data),
+        })
+            .then(function (r) { return r.json(); })
+            .then(function (resp) {
+                showToast(resp.message || '保存成功', !resp.success);
+                if (resp.success) window.location.reload();
+            })
+            .catch(function () { showToast('网络异常', true); });
+    });
+
+    function slugify(s) {
+        return s.toLowerCase().replace(/\s+/g, '-').replace(/[^a-z0-9\-]/g, '');
+    }
+})();