feat: improve error handling for video generation and update duration selection to dropdown

Co-authored-by: Copilot <copilot@github.com>

backend/app/routers/generate.py

@@ -1,6 +1,7 @@
 """Generate router: text, image, video, and image-to-video generation."""
 from datetime import datetime, timezone
 
+import httpx
 from fastapi import APIRouter, Depends, HTTPException, status
 
 from ..db import get_conn, get_write_lock
@@ -199,9 +200,16 @@ async def generate_video(
             aspect_ratio=body.aspect_ratio,
             resolution=body.resolution,
         )
+    except httpx.HTTPStatusError as exc:
+        detail = (
+            f"OpenRouter API error: {exc.response.status_code} - {exc.response.text}"
+        )
+        raise HTTPException(
+            status_code=status.HTTP_502_BAD_GATEWAY, detail=detail)
     except Exception as exc:
         raise HTTPException(
-            status_code=status.HTTP_502_BAD_GATEWAY, detail=f"OpenRouter error: {exc}")
+            status_code=status.HTTP_502_BAD_GATEWAY, detail=f"OpenRouter error: {exc}"
+        )
 
     user_id = current_user.get("id") or current_user.get("sub")
     job_id = result.get("id", "")
@@ -245,9 +253,16 @@ async def generate_video_from_image(
             aspect_ratio=body.aspect_ratio,
             resolution=body.resolution,
         )
+    except httpx.HTTPStatusError as exc:
+        detail = (
+            f"OpenRouter API error: {exc.response.status_code} - {exc.response.text}"
+        )
+        raise HTTPException(
+            status_code=status.HTTP_502_BAD_GATEWAY, detail=detail)
     except Exception as exc:
         raise HTTPException(
-            status_code=status.HTTP_502_BAD_GATEWAY, detail=f"OpenRouter error: {exc}")
+            status_code=status.HTTP_502_BAD_GATEWAY, detail=f"OpenRouter error: {exc}"
+        )
 
     user_id = current_user.get("id") or current_user.get("sub")
     job_id = result.get("id", "")