Lagerorte: Baum-Picker beim Anlegen; Unter-Ort-Bestand zählt zum Bedarf

- Web: der übergeordnete Lagerort wird beim Anlegen jetzt über den
  aufklappbaren Baum (CategorySelect) gewählt statt über das flache Dropdown.
- Backend: Mindestbestand je Lagerort wird jetzt gegen den Bestand INKL. aller
  Unter-Lagerorte geprueft. Ein Bedarf auf „Hedingen" gilt also als gedeckt,
  wenn der Vorrat in „Hedingen -> Keller" liegt. Helfer
  location_subtree_stock_base; 2 neue Tests, Suite 157 gruen.

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

backend/app/routers/views.py

@@ -26,7 +26,7 @@ from ..schemas import (
     ShoppingItem,
 )
 from ..services.conversion import BASE_OF_KIND, article_unit, display_unit_info
-from ..services.stock import current_stock, location_stock_base
+from ..services.stock import current_stock, location_subtree_stock_base
 from .settings import get_expiry_warning_days
 
 router = APIRouter(tags=["views"])
@@ -115,7 +115,7 @@ def shopping_list_by_location(
         if product is None:
             continue
         faktor, label = article_unit(product)
-        stock = location_stock_base(db, product, e.location_id) / (faktor or 1.0)
+        stock = location_subtree_stock_base(db, product, e.location_id) / (faktor or 1.0)
         if stock < e.min_stock:
             prod_needs[e.location_id].append(LocationNeedProduct(
                 product_id=product.id, name=product.name, unit_label=label,
@@ -131,10 +131,10 @@ def shopping_list_by_location(
         if unit is not None:
             base = BASE_OF_KIND[unit.kind]
             matching = [p for p in group.products if p.base_unit == base]
-            stock = sum(location_stock_base(db, p, e.location_id) for p in matching) / unit.factor
+            stock = sum(location_subtree_stock_base(db, p, e.location_id) for p in matching) / unit.factor
             unit_name = unit.name
         else:
-            stock = float(sum(location_stock_base(db, p, e.location_id) for p in group.products))
+            stock = float(sum(location_subtree_stock_base(db, p, e.location_id) for p in group.products))
             unit_name = ""
         if stock < e.min_stock:
             group_needs[e.location_id].append(LocationNeedGroup(

backend/app/services/stock.py

@@ -7,7 +7,16 @@ from datetime import date
 from sqlalchemy import asc
 from sqlalchemy.orm import Session
 
-from ..models import DatePrecision, Item, Lot, Movement, MovementType, Product, User
+from ..models import (
+    DatePrecision,
+    Item,
+    Location,
+    Lot,
+    Movement,
+    MovementType,
+    Product,
+    User,
+)
 from .conversion import to_base
 from .dates import clean_precision, normalize_best_before
 
@@ -226,6 +235,29 @@ def location_stock_base(db: Session, product: Product, location_id: int) -> floa
     return float(sum(q for (q,) in total))
 
 
+def descendant_location_ids(db: Session, location_id: int) -> set[int]:
+    """Alle Unter-Lagerorte (rekursiv) eines Lagerorts."""
+    result: set[int] = set()
+    stack = [location_id]
+    while stack:
+        cur = stack.pop()
+        for (lid,) in db.query(Location.id).filter(Location.parent_id == cur).all():
+            if lid not in result:
+                result.add(lid)
+                stack.append(lid)
+    return result
+
+
+def location_subtree_stock_base(db: Session, product: Product, location_id: int) -> float:
+    """Bestand an einem Lagerort INKL. aller Unter-Lagerorte (Basiseinheiten).
+
+    So gilt ein Mindestbestand auf „Hedingen" als gedeckt, wenn der Vorrat
+    irgendwo darunter liegt (z.B. „Hedingen → Keller").
+    """
+    ids = {location_id} | descendant_location_ids(db, location_id)
+    return float(sum(location_stock_base(db, product, lid) for lid in ids))
+
+
 def check_in(
     db: Session,
     product: Product,