feat: complete Smartgift AI Laravel unit testing toolkit

- Add 10 core testing guides (setup, AAA principles, PHPUnit/Pest, mocking, anti-patterns, PHP 8.4+, debugging, data factories, advanced edge cases)
- Add 13 component testing guides covering all Laravel layers
- Add standard templates for PHPUnit 10/11 and Pest v2/v3 including ArchitectureTest
- Add Docker smart test runner, dependency installer, and CI/CD templates (GitHub Actions, GitLab CI)
- Add 4 Claude Code skills (laravel-test-setup, laravel-unit-test with --all mode, laravel-test-review, laravel-mock-helper)
- Add single unified installer script (sg-install-unit-testing.sh) with global support, CLI runners, and 1-click updater (sg-test-update)
- Add comprehensive documentation (README.md, USAGE-GUIDE.md)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

templates/configs/.env.testing.template

@@ -0,0 +1,28 @@
+# Môi trường cách ly cho Unit & Feature Tests Laravel
+APP_NAME="Laravel Test"
+APP_ENV=testing
+APP_KEY=base64:FakeKeyForTestingPurposesOnly1234567890=
+APP_DEBUG=true
+APP_URL=http://localhost
+
+LOG_CHANNEL=null
+LOG_LEVEL=emergency
+
+# Database SQLite in-memory siêu tốc
+DB_CONNECTION=sqlite
+DB_DATABASE=:memory:
+
+# Tối ưu mã hóa mật khẩu khi chạy test
+BCRYPT_ROUNDS=4
+
+# Chặn gửi mail / queue / cache / session thật
+CACHE_STORE=array
+CACHE_DRIVER=array
+QUEUE_CONNECTION=sync
+SESSION_DRIVER=array
+MAIL_MAILER=array
+
+# Tắt các monitoring package
+TELESCOPE_ENABLED=false
+PULSE_ENABLED=false
+HORIZON_PREFIX=testing-horizon