feat: implement My Trees, admin UI, rating modal, and bundle optimization (Issues #15, #18, #19, #31)

Frontend features:
- My Trees personal dashboard with fork tracking (Issue #15)
- Tree sharing UI with token generation and copy (Issue #16)
- Draft tree badges and validation UI (Issue #25)
- Save session as tree modal (Issue #17)
- Rate/review modal with localStorage tracking (Issue #19)
- Admin category management with drag-and-drop (Issue #18)
- Bundle size optimization with code splitting (Issue #31)

Components created:
- MyTreesPage: Personal tree organization
- AdminCategoriesPage: Category CRUD with @dnd-kit
- ShareTreeModal: Tree sharing interface
- SaveSessionAsTreeModal: Session conversion UI
- StepRatingModal: Post-session rating with stars
- StarRating: Reusable rating component
- PageLoader: Loading fallback for lazy routes
- CreateCategoryModal, EditCategoryModal: Admin modals

Bundle optimization:
- Reduced from 892 KB to 221 KB (75% reduction)
- Dynamic imports for 9 heavy pages
- Vendor chunk splitting for optimal caching
- 6 separate vendor chunks (react, markdown, utils, dnd, icons, state)

Dependencies added:
- @dnd-kit/core, @dnd-kit/sortable, @dnd-kit/utilities

API clients:
- stepCategories: Full CRUD for admin
- Enhanced sessions: saveAsTree endpoint
- Enhanced trees: share, fork, canPublish endpoints

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

frontend/src/types/session.ts

@@ -81,3 +81,16 @@ export interface SessionNavigationState {
   isLoading: boolean
   error: string | null
 }
+
+// Save session as tree
+export interface SaveAsTreeRequest {
+  tree_name?: string
+  description?: string
+  status: 'draft' | 'published'
+}
+
+export interface SaveAsTreeResponse {
+  tree_id: string
+  tree_name: string
+  message: string
+}

frontend/src/types/step.ts

@@ -60,6 +60,28 @@ export interface StepCategory {
   is_active: boolean
 }
 
+export interface StepCategoryListItem {
+  id: string
+  name: string
+  description?: string
+  display_order: number
+  is_active: boolean
+}
+
+export interface StepCategoryCreate {
+  name: string
+  description?: string
+}
+
+export interface StepCategoryUpdate {
+  name?: string
+  description?: string
+}
+
+export interface StepCategoryListParams {
+  include_inactive?: boolean
+}
+
 export interface StepListParams {
   visibility?: 'private' | 'team' | 'public'
   category_id?: string
@@ -97,7 +119,9 @@ export interface StepUpdate {
 export interface RatingCreate {
   rating: number
   review_text?: string
-  verified_use: boolean
+  was_helpful?: boolean
+  session_id?: string
+  is_verified_use?: boolean
 }
 
 export interface RatingUpdate {

frontend/src/types/tree.ts

@@ -57,6 +57,8 @@ export interface TreeStructure {
 }
 
 // API response types
+export type TreeStatus = 'draft' | 'published'
+
 export interface Tree {
   id: string
   name: string
@@ -71,6 +73,7 @@ export interface Tree {
   is_active: boolean
   is_public: boolean
   is_default: boolean
+  status: TreeStatus
   version: number
   created_at: string
   updated_at: string
@@ -90,6 +93,7 @@ export interface TreeListItem {
   is_active: boolean
   is_public: boolean
   is_default: boolean
+  status: TreeStatus
   version: number
   usage_count: number
   created_at: string
@@ -105,6 +109,7 @@ export interface TreeCreate {
   tree_structure: TreeStructure
   is_public?: boolean
   is_default?: boolean
+  status?: TreeStatus
 }
 
 export interface TreeUpdate {
@@ -116,6 +121,7 @@ export interface TreeUpdate {
   tree_structure?: TreeStructure
   is_active?: boolean
   is_public?: boolean
+  status?: TreeStatus
 }
 
 // Filter params for tree listing
@@ -127,7 +133,55 @@ export interface TreeFilters {
   is_active?: boolean
   author_id?: string
   is_public?: boolean
+  include_drafts?: boolean
   sort_by?: 'usage_count' | 'updated_at' | 'created_at' | 'name' | 'name_desc' | 'version'
   skip?: number
   limit?: number
 }
+
+// Tree sharing types
+export type TreeVisibility = 'private' | 'team' | 'link' | 'public'
+
+export interface TreeShareCreate {
+  allow_forking?: boolean
+  expires_at?: string | null
+}
+
+export interface TreeShare {
+  id: string
+  tree_id: string
+  share_token: string
+  share_url: string
+  allow_forking: boolean
+  created_by: string
+  created_at: string
+  expires_at: string | null
+}
+
+export interface TreeVisibilityUpdate {
+  visibility: TreeVisibility
+}
+
+export interface SharedTree {
+  id: string
+  name: string
+  description: string | null
+  category: string | null
+  tree_structure: TreeStructure
+  tags: string[]
+  version: number
+  allow_forking: boolean
+  created_at: string
+  updated_at: string
+}
+
+// Tree validation types
+export interface ValidationError {
+  field: string
+  message: string
+}
+
+export interface TreeValidationResponse {
+  can_publish: boolean
+  errors: ValidationError[]
+}