fix: Rezeptverlauf-Bilder lokal speichern und Windows-Subprocess-Fix

- Bilder beim Extrahieren lokal cachen (data/images/{id}.ext) und über GET /api/history/{id}/image ausliefern; Löschen bei Verlaufseintrag-Entfernung
- history.db in ./data/ Volume verschoben, damit sie Container-Rebuilds überlebt
- yt-dlp Subprocess-Aufrufe auf Windows gefixt: run_in_executor statt asyncio.create_subprocess_exec (SelectorEventLoop-Kompatibilität)
- ./data:/app/data Docker-Volume für persistente Datenhaltung hinzugefügt

app/services/history_service.py

@@ -11,7 +11,7 @@ from app.config import get_settings
 
 def _db_path() -> Path:
     settings = get_settings()
-    return Path(settings.tmp_dir).parent / "history.db"
+    return Path(settings.images_dir).parent / "history.db"
 
 
 def init_db() -> None:
@@ -73,6 +73,15 @@ def delete_recipe(history_id: int) -> None:
         conn.commit()
 
 
+def update_image_url(history_id: int, image_url: str) -> None:
+    with sqlite3.connect(_db_path()) as conn:
+        conn.execute(
+            "UPDATE recipe_history SET image_url = ? WHERE id = ?",
+            (image_url, history_id),
+        )
+        conn.commit()
+
+
 def mark_imported(history_id: int, tandoor_recipe_id: Optional[int]) -> None:
     now = datetime.now(timezone.utc).isoformat()
     with sqlite3.connect(_db_path()) as conn:

app/services/image_service.py

@@ -0,0 +1,50 @@
+"""Local image caching for recipe history."""
+from __future__ import annotations
+import logging
+from pathlib import Path
+from typing import Optional
+
+import httpx
+
+from app.config import get_settings
+
+log = logging.getLogger(__name__)
+
+MIME_TO_EXT = {
+    "image/jpeg": "jpg",
+    "image/png": "png",
+    "image/webp": "webp",
+    "image/gif": "gif",
+}
+
+
+def images_dir() -> Path:
+    p = Path(get_settings().images_dir)
+    p.mkdir(parents=True, exist_ok=True)
+    return p
+
+
+def find_cached_image(history_id: int) -> Optional[Path]:
+    """Return the cached image Path for a history entry, or None."""
+    for ext in MIME_TO_EXT.values():
+        p = images_dir() / f"{history_id}.{ext}"
+        if p.exists():
+            return p
+    return None
+
+
+async def download_and_cache(history_id: int, remote_url: str) -> Optional[str]:
+    """Download image from remote_url, save locally, return local API path or None on failure."""
+    try:
+        async with httpx.AsyncClient(timeout=15) as client:
+            resp = await client.get(remote_url, follow_redirects=True)
+            resp.raise_for_status()
+            ct = resp.headers.get("content-type", "image/jpeg").split(";")[0].strip()
+            ext = MIME_TO_EXT.get(ct, "jpg")
+            dest = images_dir() / f"{history_id}.{ext}"
+            dest.write_bytes(resp.content)
+            log.info("Cached image for history %d → %s", history_id, dest)
+            return f"/api/history/{history_id}/image"
+    except Exception as exc:
+        log.warning("Image cache failed for history %d: %s", history_id, exc)
+        return None