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

internal/router/admin.go

@@ -33,6 +33,7 @@ func setupAdminRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		adminPages.GET("/energy/fund-logs", d.adminEnergyCtrl.FundLogPage)
 		adminPages.GET("/comments", d.adminCommentCtrl.CommentsPage)
 		adminPages.GET("/announcements", d.announcementCtrl.Page)
+		adminPages.GET("/categories", d.categoryCtrl.Page)
 	}
 
 	// --- 管理后台 API ---
@@ -115,4 +116,17 @@ func setupAdminRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		announcementAPI.PUT("/:id", d.announcementCtrl.Update)
 		announcementAPI.DELETE("/:id", d.announcementCtrl.Delete)
 	}
+
+	// --- 分类管理 API（moderator+） ---
+	categoryAPI := r.Group("/api/admin/categories")
+	categoryAPI.Use(d.authMdw.Required())
+	categoryAPI.Use(middleware.RequireMinRole(model.RoleModerator))
+	categoryAPI.Use(d.authMdw.BannedWriteGuard())
+	categoryAPI.Use(middleware.CSRF(cfg))
+	{
+		categoryAPI.GET("", d.categoryCtrl.List)
+		categoryAPI.POST("", d.categoryCtrl.Create)
+		categoryAPI.PUT("/:id", d.categoryCtrl.Update)
+		categoryAPI.DELETE("/:id", d.categoryCtrl.Delete)
+	}
 }