Add tree organization system with categories, tags, and folders

Features:
- Categories: Global and team-specific tree categorization (admin-managed)
- Tags: Flexible tree tagging with autocomplete (author + admin)
- User folders: Personal tree collections with subfolder support
  - Hierarchical structure (max 3 levels deep)
  - Right-click context menu for folder management
  - Cascade delete for subfolders
- Filter trees by category, tags, and folder in library view

Backend:
- New models: Category, Tag, UserFolder with relationships
- New API endpoints for categories, tags, and folders
- Tree organization migrations (005, 006)

Frontend:
- FolderSidebar with hierarchical folder tree
- FolderEditModal for create/edit with color picker
- AddToFolderMenu for quick tree organization
- TagInput with autocomplete and TagBadges display
- Updated TreeMetadataForm and TreeLibraryPage

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/store/treeEditorStore.ts

@@ -101,6 +101,9 @@ interface TreeEditorState {
   name: string
   description: string
   category: string
+  categoryId: string | null
+  tags: string[]
+  isPublic: boolean
   treeStructure: TreeStructure | null
   originalTree: Tree | null // For comparison in edit mode
 
@@ -127,6 +130,11 @@ interface TreeEditorState {
   setName: (name: string) => void
   setDescription: (description: string) => void
   setCategory: (category: string) => void
+  setCategoryId: (categoryId: string | null) => void
+  setTags: (tags: string[]) => void
+  addTag: (tag: string) => void
+  removeTag: (tag: string) => void
+  setIsPublic: (isPublic: boolean) => void
 
   // Actions - Node CRUD
   addNode: (parentId: string | null, type: NodeType, insertIndex?: number) => string
@@ -169,6 +177,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
       name: '',
       description: '',
       category: '',
+      categoryId: null,
+      tags: [],
+      isPublic: false,
       treeStructure: null,
       originalTree: null,
       selectedNodeId: null,
@@ -188,6 +199,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
           state.name = ''
           state.description = ''
           state.category = ''
+          state.categoryId = null
+          state.tags = []
+          state.isPublic = false
           state.treeStructure = {
             id: 'root',
             type: 'decision',
@@ -213,6 +227,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
           state.name = tree.name
           state.description = tree.description || ''
           state.category = tree.category || ''
+          state.categoryId = tree.category_id || null
+          state.tags = tree.tags || []
+          state.isPublic = tree.is_public || false
           state.treeStructure = tree.tree_structure
           state.originalTree = tree
           state.selectedNodeId = tree.tree_structure?.id || null
@@ -236,6 +253,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
             state.name = draft.name || ''
             state.description = draft.description || ''
             state.category = draft.category || ''
+            state.categoryId = draft.categoryId || null
+            state.tags = draft.tags || []
+            state.isPublic = draft.isPublic || false
             state.treeStructure = draft.treeStructure || null
             state.isDirty = true
             state.draftSavedAt = draft.savedAt ? new Date(draft.savedAt) : null
@@ -261,6 +281,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
           state.name = ''
           state.description = ''
           state.category = ''
+          state.categoryId = null
+          state.tags = []
+          state.isPublic = false
           state.treeStructure = null
           state.originalTree = null
           state.selectedNodeId = null
@@ -299,6 +322,48 @@ export const useTreeEditorStore = create<TreeEditorState>()(
         get().autoSaveDraft()
       },
 
+      setCategoryId: (categoryId: string | null) => {
+        set((state) => {
+          state.categoryId = categoryId
+          state.isDirty = true
+        })
+        get().autoSaveDraft()
+      },
+
+      setTags: (tags: string[]) => {
+        set((state) => {
+          state.tags = tags
+          state.isDirty = true
+        })
+        get().autoSaveDraft()
+      },
+
+      addTag: (tag: string) => {
+        set((state) => {
+          if (!state.tags.includes(tag)) {
+            state.tags.push(tag)
+            state.isDirty = true
+          }
+        })
+        get().autoSaveDraft()
+      },
+
+      removeTag: (tag: string) => {
+        set((state) => {
+          state.tags = state.tags.filter(t => t !== tag)
+          state.isDirty = true
+        })
+        get().autoSaveDraft()
+      },
+
+      setIsPublic: (isPublic: boolean) => {
+        set((state) => {
+          state.isPublic = isPublic
+          state.isDirty = true
+        })
+        get().autoSaveDraft()
+      },
+
       // Node CRUD
       addNode: (parentId: string | null, type: NodeType, insertIndex?: number) => {
         const newId = generateId()
@@ -605,6 +670,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
           name: state.name,
           description: state.description,
           category: state.category,
+          categoryId: state.categoryId,
+          tags: state.tags,
+          isPublic: state.isPublic,
           treeStructure: state.treeStructure,
           savedAt: new Date().toISOString()
         }
@@ -628,6 +696,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
           name: state.name,
           description: state.description || undefined,
           category: state.category || undefined,
+          category_id: state.categoryId || undefined,
+          tags: state.tags.length > 0 ? state.tags : undefined,
+          is_public: state.isPublic,
           tree_structure: state.treeStructure!
         }
       },
@@ -694,6 +765,9 @@ export const useTreeEditorStore = create<TreeEditorState>()(
         name: state.name,
         description: state.description,
         category: state.category,
+        categoryId: state.categoryId,
+        tags: state.tags,
+        isPublic: state.isPublic,
         treeStructure: state.treeStructure
       })
     }