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

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

frontend/stores/auth.ts

@@ -58,6 +58,14 @@ export const useAuthStore = defineStore('auth', {
                 this.checked = true
                 this.isLoading = false
             }
+        },
+        async refreshUser() {
+            try {
+                const me = await getCurrentUser()
+                this.user = me
+            } catch {
+                // Silently fail — user session might have expired
+            }
         }
     }
 })