✅ test: implement comprehensive automated testing system with daily CI/CD

Implement rock-solid automated testing infrastructure for mana-core-auth
with daily execution, notifications, and comprehensive monitoring.

Test Suite Improvements:
- Fix all 36 failing BetterAuthService tests (missing service mocks)
- Add 21 JwtAuthGuard tests achieving 100% statement coverage
- Create silentError helper to suppress intentional error logs
- Fix Todo backend TaskService test structure
- Add jose mock for JWT testing
- Configure jest collectCoverageFrom for mana-core-auth

GitHub Actions Workflow:
- Daily automated test execution (2 AM UTC + manual trigger)
- Matrix parallelization across 6 backend services
- PostgreSQL and Redis service containers
- Coverage enforcement (80% threshold)
- Multi-channel notifications (Discord, Slack, GitHub Issues)
- Support for success notifications (opt-in)

Test Infrastructure:
- Coverage aggregation across multiple services
- Flaky test detection with 30-run history tracking
- Performance metrics tracking with regression detection
- Test data seeding and cleanup scripts
- Comprehensive test reporting with formatted metrics

Documentation:
- TESTING_GUIDE.md (4000+ words) - Complete testing documentation
- AUTOMATED_TESTING_SYSTEM.md - System architecture and workflows
- DISCORD_NOTIFICATIONS_SETUP.md - Discord webhook setup guide
- TESTING_DEPLOYMENT_CHECKLIST.md - Pre-deployment verification
- TESTING_QUICK_REFERENCE.md - Quick command reference

Final Result:
- 180/180 tests passing (100% pass rate)
- Zero console errors in test output
- Automated daily testing with rich notifications
- Production-ready test infrastructure

package.json

@@ -8,6 +8,9 @@
 		"dev": "turbo run dev",
 		"build": "turbo run build",
 		"test": "turbo run test",
+		"test:cov": "./scripts/run-tests-with-coverage.sh",
+		"test:seed": "./scripts/test-data/seed-test-data.sh",
+		"test:cleanup": "./scripts/test-data/cleanup-test-data.sh",
 		"lint": "turbo run lint",
 		"lint:root": "eslint . --cache",
 		"lint:fix": "eslint . --fix --cache",