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/models/__init__.py

@@ -49,6 +49,10 @@ from app.modules.loyalty.models.staff_pin import (
     # Model
     StaffPin,
 )
+from app.modules.loyalty.models.transaction_category import (
+    # Model
+    StoreTransactionCategory,
+)
 
 __all__ = [
     # Enums
@@ -62,4 +66,5 @@ __all__ = [
     "StaffPin",
     "AppleDeviceRegistration",
     "MerchantLoyaltySettings",
+    "StoreTransactionCategory",
 ]

app/modules/loyalty/models/loyalty_transaction.py

@@ -104,6 +104,12 @@ class LoyaltyTransaction(Base, TimestampMixin):
         index=True,
         comment="Staff PIN used for this operation",
     )
+    category_id = Column(
+        Integer,
+        ForeignKey("store_transaction_categories.id", ondelete="SET NULL"),
+        nullable=True,
+        comment="Product category (e.g., Men, Women, Accessories)",
+    )
 
     # Related transaction (for voids/returns)
     related_transaction_id = Column(

app/modules/loyalty/models/transaction_category.py

@@ -0,0 +1,44 @@
+# app/modules/loyalty/models/transaction_category.py
+"""
+Store-scoped transaction categories.
+
+Merchants configure 4-10 categories per store (e.g., Men, Women,
+Accessories, Kids) that sellers select when entering transactions.
+"""
+
+from sqlalchemy import (
+    Boolean,
+    Column,
+    ForeignKey,
+    Index,
+    Integer,
+    String,
+    UniqueConstraint,
+)
+from sqlalchemy.orm import relationship
+
+from app.core.database import Base
+from models.database.base import TimestampMixin
+
+
+class StoreTransactionCategory(Base, TimestampMixin):
+    """Product category for loyalty transactions."""
+
+    __tablename__ = "store_transaction_categories"
+
+    id = Column(Integer, primary_key=True, index=True)
+    store_id = Column(Integer, ForeignKey("stores.id"), nullable=False)
+    name = Column(String(100), nullable=False)
+    display_order = Column(Integer, nullable=False, default=0)
+    is_active = Column(Boolean, nullable=False, default=True)
+
+    # Relationships
+    store = relationship("Store")
+
+    __table_args__ = (
+        UniqueConstraint("store_id", "name", name="uq_store_category_name"),
+        Index("idx_store_category_store", "store_id", "is_active"),
+    )
+
+    def __repr__(self):
+        return f"<StoreTransactionCategory(id={self.id}, store={self.store_id}, name='{self.name}')>"