feat: add ForkInfo type and fork fields to Tree/TreeListItem

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/types/tree.ts

@@ -139,6 +139,14 @@ export interface ProceduralTreeStructure {
   steps: ProceduralStep[]
 }
 
+export interface ForkInfo {
+  parent_tree_id: string
+  parent_tree_name: string | null
+  fork_depth: number
+  fork_reason: string | null
+  has_parent_updates: boolean
+}
+
 // API response types
 export type TreeStatus = 'draft' | 'published'
 
@@ -164,6 +172,9 @@ export interface Tree {
   created_at: string
   updated_at: string
   usage_count: number
+  fork_info?: ForkInfo | null
+  parent_tree_id?: string | null
+  fork_depth?: number
 }
 
 export interface TreeListItem {
@@ -187,6 +198,8 @@ export interface TreeListItem {
   created_at: string
   updated_at: string
   visibility: 'private' | 'team' | 'link' | 'public'
+  fork_depth?: number
+  parent_tree_id?: string | null
 }
 
 export interface TreeCreate {