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/deps_extra.go

@@ -103,6 +103,18 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 
 	maintenanceMdw := middleware.NewMaintenanceMiddleware(cfg, siteSettings, sessionMgr)
 
+	// 分类系统
+	categoryRepo := repository.NewCategoryRepo(db)
+	categoryService := service.NewCategoryService(categoryRepo)
+	categoryCtrl := adminCtrl.NewCategoryController(categoryService)
+	studioCtrl.WithCategoryService(categoryService)
+
+	// 标签系统
+	tagRepo := repository.NewTagRepo(db)
+	tagService := service.NewTagService(tagRepo)
+	tagCtrl := controller.NewTagController(tagService)
+	studioCtrl.WithTagService(tagService)
+
 	// 公告系统
 	announcementRepo := repository.NewAnnouncementRepo(db)
 	announcementService := service.NewAnnouncementService(announcementRepo)
@@ -135,5 +147,9 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 		homeCache:          homeCache,
 		announcementService: announcementService,
 		announcementCtrl:   announcementCtrl,
+		categoryCtrl:       categoryCtrl,
+		categoryService:    categoryService,
+		tagCtrl:            tagCtrl,
+		tagService:         tagService,
 	}
 }