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/Pest.template.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+|--------------------------------------------------------------------------
+| Test Case Configuration
+|--------------------------------------------------------------------------
+|
+| Định cấu hình TestCase mặc định cho Unit và Feature tests trong Pest PHP.
+|
+*/
+
+uses(
+    Tests\TestCase::class,
+    // Illuminate\Foundation\Testing\RefreshDatabase::class, // Chỉ bật trong Feature Test
+)->in('Feature');
+
+uses(
+    Tests\TestCase::class,
+)->in('Unit');
+
+/*
+|--------------------------------------------------------------------------
+| Expectations Custom Helpers
+|--------------------------------------------------------------------------
+|
+| Tạo các custom expectation mở rộng của Pest nếu cần.
+|
+*/
+
+expect()->extend('toBeValidEmail', function () {
+    return $this->toBeString()->toMatch('/^.+@.+\..+$/');
+});
+
+/*
+|--------------------------------------------------------------------------
+| Functions Helpers
+|--------------------------------------------------------------------------
+|
+| Hàm global hỗ trợ khởi tạo dữ liệu giả lập cho test.
+|
+*/
+
+// function asUser($user = null) {
+//     return test()->actingAs($user ?? User::factory()->create());
+// }