feat(T08): Bildretusche via Flux.1-Pro + Preisvergleich + Retouch UI with before/after slider

backend/app/tasks/retouch_processing.py

@@ -0,0 +1,38 @@
+"""Async retouch processing background task.
+
+Creates its own DB session independent of the request session so the
+HTTP response can return immediately while processing continues.
+"""
+
+from __future__ import annotations
+
+import logging
+import uuid
+from typing import Any
+
+from app.database import async_session_factory
+from app.services.retouch_service import process_retouch
+
+logger = logging.getLogger(__name__)
+
+
+async def run_retouch_processing(
+    result_id: uuid.UUID,
+    vehicle_info: dict[str, Any] | None = None,
+) -> None:
+    """Background task: process retouch result asynchronously.
+
+    Creates its own DB session (independent of the request session)
+    so the HTTP response can return immediately.
+    """
+    async with async_session_factory() as session:
+        try:
+            await process_retouch(session, result_id, vehicle_info)
+            await session.commit()
+            logger.info("Retouch processing completed for result %s", result_id)
+        except Exception as exc:
+            await session.rollback()
+            logger.error("Retouch background task failed for %s: %s", result_id, exc)
+            raise
+        finally:
+            await session.close()