Sprint 22 new and changed files

Application core
- app/Core/App.php
- app/Core/Text.php

Controller
- app/Http/Controllers/NotificationCollaborationController.php

Notification, queue and collaboration services
- app/Modules/NotificationsCollaboration/NotificationService.php
- app/Modules/NotificationsCollaboration/EmailQueueService.php
- app/Modules/NotificationsCollaboration/CollaborationService.php
- app/Modules/NotificationsCollaboration/SchedulerService.php

SMTP and template services
- app/Services/Mail/EmailTemplateRenderer.php
- app/Services/Mail/RetryPolicy.php
- app/Services/Mail/SmtpException.php
- app/Services/Mail/SmtpMessageBuilder.php
- app/Services/Mail/SmtpTransport.php

Database
- database/migrations/016_notifications_email_collaboration.sql
- database/views/016_notifications_collaboration_views.sql
- database/seeds/016_branded_email_templates.sql

React integration
- frontend-integration/src/notifications-collaboration/types.ts
- frontend-integration/src/notifications-collaboration/notificationCollaborationApi.ts
- frontend-integration/src/notifications-collaboration/NotificationCentrePage.tsx
- frontend-integration/src/notifications-collaboration/CollaborationPage.tsx
- frontend-integration/src/notifications-collaboration/EmailAdministrationPage.tsx
- frontend-integration/src/notifications-collaboration/notificationsCollaboration.css

CLI tools
- tools/email_worker.php
- tools/run_scheduler.php
- tools/test_smtp_server.py

Tests
- tests/notifications_collaboration_unit.php
- tests/notifications_collaboration_static.php
- tests/smtp_transport_integration.php
- tests/run_sprint22.sh
- tests/react-stubs.d.ts
- tests/tsconfig.sprint22.json

Documentation
- README_SPRINT_22.md
- docs/SPRINT_22_STATUS.md
- docs/INSTALLATION_SPRINT_22.md
- docs/SMTP_CONFIGURATION_GUIDE.md
- docs/CRON_AND_QUEUE_OPERATIONS.md
- docs/API_REFERENCE_SPRINT_22.md
- docs/NOTIFICATION_EMAIL_SECURITY_POLICY_DRAFT.md
- docs/TEST_RESULTS_SPRINT_22.txt
- docs/ALL_TEST_RESULTS_SPRINT_22.txt
- docs/LINT_RESULTS_SPRINT_22.txt
- docs/FILES_SPRINT_22.txt

Configuration
- .env.example