feat(storage): add S3 image storage support with file-based config and migration script

app/routers/api.py

@@ -13,7 +13,7 @@ from app.models import (
     PERM_POSTCARDS_READ, PERM_POSTCARDS_WRITE,
     PERM_IMAGES_UPLOAD,
 )
-from app.config import UPLOAD_DIR
+# config removed: image storage now via app.storage
 
 router = APIRouter(prefix="/api/v1", tags=["api"])
 
@@ -380,15 +380,16 @@ async def upload_image(
     ak: ApiKey = Depends(require_scopes(PERM_IMAGES_UPLOAD)),
 ):
     pc = _postcard_or_404(ak.user, profile_id, postcard_id, db)
+    from app.storage import get_storage
+    storage = get_storage()
     ext = Path(file.filename).suffix if file.filename else ".jpg"
-    save_name = f"pc_{pc.id}_{side}{ext}"
-    save_path = UPLOAD_DIR / save_name
+    key = f"pc_{pc.id}_{side}{ext}"
     content = await file.read()
-    save_path.write_bytes(content)
+    storage.put(key, content)
     if side == "front":
-        pc.image_front = f"/uploads/{save_name}"
+        pc.image_front = key
     else:
-        pc.image_back = f"/uploads/{save_name}"
+        pc.image_back = key
     db.commit()
     db.refresh(pc)
     return pc