feat(loyalty): transaction categories (what was sold)

Merchants can configure per-store product categories (e.g., Men,
Women, Accessories, Kids) that sellers select when entering loyalty
transactions. Enables per-category sales analytics.

Backend:
- New model: StoreTransactionCategory (store-scoped, max 10 per store)
- Migration loyalty_007: creates table + adds category_id FK on
  loyalty_transactions
- New category_service.py with CRUD + validation
- New schemas/category.py (Create, Update, Response, ListResponse)
- Admin CRUD: GET/POST/PATCH/DELETE /admin/loyalty/stores/{id}/categories
- Store CRUD: GET/POST/PATCH/DELETE /store/loyalty/categories
- Stamp/Points request schemas accept optional category_id
- Stamp/Points services pass category_id to transaction creation
- TransactionResponse includes category_id + category_name

342 tests pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/loyalty/routes/api/admin.py

@@ -497,6 +497,79 @@ def get_platform_stats(
     return program_service.get_platform_stats(db)
 
 
+# =============================================================================
+# Transaction Categories (admin manages on behalf of stores)
+# =============================================================================
+
+
+@router.get("/stores/{store_id}/categories")
+def list_store_categories(
+    store_id: int = Path(..., gt=0),
+    current_user: User = Depends(get_current_admin_api),
+    db: Session = Depends(get_db),
+):
+    """List transaction categories for a store."""
+    from app.modules.loyalty.schemas.category import (
+        CategoryListResponse,
+        CategoryResponse,
+    )
+    from app.modules.loyalty.services.category_service import category_service
+
+    categories = category_service.list_categories(db, store_id)
+    return CategoryListResponse(
+        categories=[CategoryResponse.model_validate(c) for c in categories],
+        total=len(categories),
+    )
+
+
+@router.post("/stores/{store_id}/categories", status_code=201)
+def create_store_category(
+    data: dict,
+    store_id: int = Path(..., gt=0),
+    current_user: User = Depends(get_current_admin_api),
+    db: Session = Depends(get_db),
+):
+    """Create a transaction category for a store."""
+    from app.modules.loyalty.schemas.category import CategoryCreate, CategoryResponse
+    from app.modules.loyalty.services.category_service import category_service
+
+    category = category_service.create_category(
+        db, store_id, CategoryCreate(**data)
+    )
+    return CategoryResponse.model_validate(category)
+
+
+@router.patch("/stores/{store_id}/categories/{category_id}")
+def update_store_category(
+    data: dict,
+    store_id: int = Path(..., gt=0),
+    category_id: int = Path(..., gt=0),
+    current_user: User = Depends(get_current_admin_api),
+    db: Session = Depends(get_db),
+):
+    """Update a transaction category for a store."""
+    from app.modules.loyalty.schemas.category import CategoryResponse, CategoryUpdate
+    from app.modules.loyalty.services.category_service import category_service
+
+    category = category_service.update_category(
+        db, category_id, store_id, CategoryUpdate(**data)
+    )
+    return CategoryResponse.model_validate(category)
+
+
+@router.delete("/stores/{store_id}/categories/{category_id}", status_code=204)
+def delete_store_category(
+    store_id: int = Path(..., gt=0),
+    category_id: int = Path(..., gt=0),
+    current_user: User = Depends(get_current_admin_api),
+    db: Session = Depends(get_db),
+):
+    """Delete a transaction category for a store."""
+    from app.modules.loyalty.services.category_service import category_service
+
+    category_service.delete_category(db, category_id, store_id)
+
+
 # =============================================================================
 # Advanced Analytics
 # =============================================================================