fix(api-client): declare moved + errors on migrateModels response type

ModelManagement.tsx reads migrationResult.moved (added in #433) but
apiClient.migrateModels() was typed as returning only { source, destination }.
The backend actually returns { moved: int, errors: list[str], source, destination }
(backend/routes/models.py:140, 168). Widen the TS return type so the check
typechecks under the new CI gate from #418.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

app/src/lib/api/client.ts

@@ -390,7 +390,9 @@ class ApiClient {
     return this.request<{ path: string }>('/models/cache-dir');
   }
 
-  async migrateModels(destination: string): Promise<{ source: string; destination: string }> {
+  async migrateModels(
+    destination: string,
+  ): Promise<{ source: string; destination: string; moved: number; errors: string[] }> {
     return this.request('/models/migrate', {
       method: 'POST',
       body: JSON.stringify({ destination }),