实现知识库两级分类树与完整 CRUD

支持父子分类、展开侧栏与改删校验；选中父分类可筛子级条目；对齐左右顶栏并更新种子树形数据。

server/internal/handler/router.go

@@ -76,6 +76,8 @@ func SetupRoutes(r *gin.Engine, store storage.ObjectStorage, storageCfg config.S
 		kb := authRequired.Group("/knowledge")
 		kb.GET("/categories", knowledge.ListCategories)
 		kb.POST("/categories", knowledge.CreateCategory)
+		kb.PUT("/categories/:id", knowledge.UpdateCategory)
+		kb.DELETE("/categories/:id", knowledge.DeleteCategory)
 		kb.GET("/entries", knowledge.ListEntries)
 		kb.POST("/entries", knowledge.CreateEntry)
 		kb.PUT("/entries/:id", knowledge.UpdateEntry)