test: add Pest browser testing with SQLite :memory: schema

Set up end-to-end browser testing using Pest Browser Plugin + Playwright.
New v4 test suite uses SQLite :memory: database with pre-generated schema dump
(database/schema/testing-schema.sql) instead of running migrations, enabling
faster test startup.

- Add pestphp/pest-plugin-browser dependency
- Create GenerateTestingSchema command to export PostgreSQL schema to SQLite
- Add .env.testing configuration for isolated test environment
- Implement v4 test directory structure (Feature, Browser, Unit tests)
- Update Pest skill documentation with browser testing patterns, API reference,
  debugging techniques, and common pitfalls
- Configure phpunit.xml and tests/Pest.php for v4 suite
- Update package.json and docker-compose.dev.yml for testing dependencies

resources/views/auth/register.blade.php

@@ -1,7 +1,9 @@
 <?php
-function getOldOrLocal($key, $localValue)
-{
-    return old($key) != '' ? old($key) : (app()->environment('local') ? $localValue : '');
+if (! function_exists('getOldOrLocal')) {
+    function getOldOrLocal($key, $localValue)
+    {
+        return old($key) != '' ? old($key) : (app()->environment('local') ? $localValue : '');
+    }
 }
 
 $name = getOldOrLocal('name', 'test3 normal user');