feat(avatar) : add avatar service, DTO update, and cropper dependency

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/services/dto/user-data.ts

@@ -7,6 +7,7 @@ export type UserData = {
     roles: string[]
     client?: { id: number; name: string } | null
     allowedProjects?: Project[]
+    avatarUrl?: string | null
 }
 
 export type UserWrite = {