Fix: Move notifications to SHARED_APPS for platform-to-tenant notifications

Platform users need to send notifications to business tenants, so the
notifications app must be in SHARED_APPS (public schema) rather than
TENANT_APPS (tenant-specific schemas).

Changes:
- Moved notifications from TENANT_APPS to SHARED_APPS in multitenancy.py
- Run migrations on public schema to create notifications tables

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

smoothschedule/config/settings/multitenancy.py

@@ -45,6 +45,7 @@ SHARED_APPS = [
     'csp',
     'djstripe',  # Stripe integration
     'tickets', # Ticket system - shared for platform support access
+    'notifications', # Notification system - shared for platform to notify tenants
     'smoothschedule.public_api', # Public API v1 for third-party integrations
 ]
 
@@ -54,7 +55,6 @@ TENANT_APPS = [
     'schedule',  # Resource scheduling with configurable concurrency
     'payments',  # Stripe Connect payments bridge
     'communication',  # Twilio masked communications
-    'notifications', # New: Generic notification app
     # Add your tenant-scoped business logic apps here:
     # 'appointments',
     # 'customers',