feat: implement timeout handling and error messages for image generation

frontend/app/helpers.py

@@ -12,9 +12,10 @@ def _backend(path: str) -> str:
 
 def _api(method: str, path: str, *, token: str | None = None, **kwargs):
     headers = kwargs.pop("headers", {})
+    timeout = kwargs.pop("timeout", 30)
     if token:
         headers["Authorization"] = f"Bearer {token}"
-    return httpx.request(method, _backend(path), headers=headers, timeout=30, **kwargs)
+    return httpx.request(method, _backend(path), headers=headers, timeout=timeout, **kwargs)
 
 
 def _model_matches_modality(model: dict, modality: str) -> bool: