feat: add Phase 2 migration, make urls command, fix seed script

- Create loyalty_003 migration: company-based architecture (adds
  company_id to all loyalty tables, creates company_loyalty_settings,
  renames vendor_id to enrolled_at_vendor_id on cards)
- Move platform migration back to alembic/versions (not loyalty-specific)
- Add version_locations to alembic.ini for module migration discovery
- Add make urls/urls-dev/urls-prod commands (scripts/show_urls.py)
- Fix seed_demo.py: import all module models to resolve SQLAlchemy
  string relationships, fix multiple admin query, set platform_id
  on vendor content pages
- Fix loyalty test fixtures to match Phase 2 model columns

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/seed_demo.py

@@ -51,21 +51,37 @@ from app.core.config import settings
 from app.core.database import SessionLocal
 from app.core.environment import get_environment, is_production
 from middleware.auth import AuthManager
-from app.modules.cms.models import ContentPage
-from app.modules.tenancy.models import PlatformAlert
-from app.modules.tenancy.models import Company
+# =============================================================================
+# MODEL IMPORTS
+# =============================================================================
+# ALL models must be imported before any ORM query so SQLAlchemy can resolve
+# cross-module string relationships (e.g. Vendor→VendorEmailTemplate,
+# Platform→SubscriptionTier, Product→Inventory).
+
+# Core modules
+from app.modules.tenancy.models import Company, PlatformAlert, User, Role, Vendor, VendorUser, VendorDomain
+from app.modules.cms.models import ContentPage, VendorTheme
+from app.modules.catalog.models import Product
 from app.modules.customers.models.customer import Customer, CustomerAddress
+from app.modules.orders.models import Order, OrderItem
 from app.modules.marketplace.models import (
     MarketplaceImportJob,
     MarketplaceProduct,
     MarketplaceProductTranslation,
 )
-from app.modules.orders.models import Order, OrderItem
-from app.modules.catalog.models import Product
-from app.modules.tenancy.models import User
-from app.modules.tenancy.models import Role, Vendor, VendorUser
-from app.modules.tenancy.models import VendorDomain
-from app.modules.cms.models import VendorTheme
+
+# Optional modules — import to register models with SQLAlchemy
+for _mod in [
+    "app.modules.inventory.models",
+    "app.modules.cart.models",
+    "app.modules.billing.models",
+    "app.modules.messaging.models",
+    "app.modules.loyalty.models",
+]:
+    try:
+        __import__(_mod)
+    except ImportError:
+        pass
 
 SEED_MODE = os.getenv("SEED_MODE", "normal")  # normal, minimal, reset
 FORCE_RESET = os.getenv("FORCE_RESET", "false").lower() in ("true", "1", "yes")
@@ -394,7 +410,7 @@ def check_environment():
 def check_admin_exists(db: Session) -> bool:
     """Check if admin user exists."""
 
-    admin = db.execute(select(User).where(User.role == "admin")).scalar_one_or_none()
+    admin = db.execute(select(User).where(User.role == "admin").limit(1)).scalar_one_or_none()
 
     if not admin:
         print_error("No admin user found!")
@@ -799,6 +815,14 @@ def create_demo_vendor_content_pages(db: Session, vendors: list[Vendor]) -> int:
     """
     created_count = 0
 
+    # Get the OMS platform ID (vendors are registered on OMS)
+    from app.modules.tenancy.models import Platform
+
+    oms_platform = db.execute(
+        select(Platform).where(Platform.code == "oms")
+    ).scalar_one_or_none()
+    default_platform_id = oms_platform.id if oms_platform else 1
+
     for vendor in vendors:
         vendor_pages = VENDOR_CONTENT_PAGES.get(vendor.vendor_code, [])
 
@@ -819,6 +843,7 @@ def create_demo_vendor_content_pages(db: Session, vendors: list[Vendor]) -> int:
 
             # Create vendor content page override
             page = ContentPage(
+                platform_id=default_platform_id,
                 vendor_id=vendor.id,
                 slug=page_data["slug"],
                 title=page_data["title"],