Schritt 1: Fundament der Lebensmittel-Lagerverwaltung (Pantry)

Backend (FastAPI + PostgreSQL): Chargen mit MHD, FEFO-Auslagern,
Einheiten-Umrechnung (Stueck/g/ml + Packungen), Open-Food-Facts-Lookup
mit lokalem Fallback, JWT-Auth mit Rollen (Admin/Nutzer), erster Admin
beim Setup, Einkaufsliste, Ablaufwarnung, Lagerorte, pytest fuer FEFO.

Web-UI (React/Vite): Login, Dashboard, Ein-/Auslagern, Produkte,
Lagerorte, Benutzerverwaltung, Einkaufsliste - rollenabhaengig.

Deploy: docker-compose + install.sh (Docker-Autoinstall, Secrets),
README und Roadmap fuer Schritt 2 (iOS) und Schritt 3.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/routers/stock.py

@@ -0,0 +1,83 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from ..crud import resolve_product
+from ..database import get_db
+from ..deps import get_current_user
+from ..models import Lot, User
+from ..schemas import (
+    CheckInRequest,
+    CheckInResponse,
+    CheckOutRequest,
+    CheckOutResponse,
+    LotOut,
+)
+from ..services.stock import StockError, check_in, check_out, current_stock
+from ..services.units import UnitError
+
+router = APIRouter(tags=["stock"])
+
+
+@router.post("/stock/checkin", response_model=CheckInResponse)
+def stock_checkin(
+    payload: CheckInRequest,
+    db: Session = Depends(get_db),
+    user: User = Depends(get_current_user),
+) -> CheckInResponse:
+    product = resolve_product(db, payload.product_id, payload.barcode)
+    try:
+        lot = check_in(
+            db,
+            product=product,
+            quantity=payload.quantity,
+            unit=payload.unit,
+            best_before=payload.best_before,
+            location_id=payload.location_id,
+            user=user,
+            note=payload.note,
+        )
+    except UnitError as exc:
+        raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
+    db.commit()
+    db.refresh(lot)
+    return CheckInResponse(
+        lot=LotOut.model_validate(lot), product_stock=current_stock(db, product.id)
+    )
+
+
+@router.post("/stock/checkout", response_model=CheckOutResponse)
+def stock_checkout(
+    payload: CheckOutRequest,
+    db: Session = Depends(get_db),
+    user: User = Depends(get_current_user),
+) -> CheckOutResponse:
+    product = resolve_product(db, payload.product_id, payload.barcode)
+    try:
+        affected = check_out(
+            db,
+            product=product,
+            quantity=payload.quantity,
+            unit=payload.unit,
+            user=user,
+            note=payload.note,
+        )
+    except UnitError as exc:
+        raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
+    except StockError as exc:
+        raise HTTPException(status.HTTP_409_CONFLICT, str(exc)) from exc
+    db.commit()
+    return CheckOutResponse(
+        affected_lots=affected, product_stock=current_stock(db, product.id)
+    )
+
+
+@router.get("/lots", response_model=list[LotOut])
+def list_lots(
+    product_id: int | None = None,
+    db: Session = Depends(get_db),
+    _: User = Depends(get_current_user),
+) -> list[Lot]:
+    query = db.query(Lot)
+    if product_id is not None:
+        query = query.filter(Lot.product_id == product_id)
+    return query.order_by(Lot.best_before.is_(None), Lot.best_before).all()