fix(scripts): fix model registration and missing platform_id in init scripts

All init scripts (init_log_settings, create_default_content_pages,
create_platform_pages, seed_email_templates) failed because they didn't
register all SQLAlchemy model classes, causing mapper resolution errors
for cross-module relationships (Platform→ContentPage, Platform→SubscriptionTier).

Fixes:
- Add full model registration loop to all 5 init scripts
- Add platform_id (OMS) to content page creation (NOT NULL constraint)
- Add missing db.commit() to create_platform_pages.py (pages were never persisted)
- Add cms.models to init_production.py registration list

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

scripts/seed_email_templates.py

@@ -12,6 +12,24 @@ from pathlib import Path
 # Add project root to path
 sys.path.insert(0, str(Path(__file__).parent.parent))
 
+# Register all models with SQLAlchemy so string-based relationships resolve
+for _mod in [
+    "app.modules.billing.models",
+    "app.modules.inventory.models",
+    "app.modules.cart.models",
+    "app.modules.messaging.models",
+    "app.modules.loyalty.models",
+    "app.modules.catalog.models",
+    "app.modules.customers.models",
+    "app.modules.orders.models",
+    "app.modules.marketplace.models",
+    "app.modules.cms.models",
+]:
+    try:
+        __import__(_mod)
+    except ImportError:
+        pass
+
 from app.core.database import get_db
 from app.modules.messaging.models import EmailCategory, EmailTemplate