feat: Phase 4 - CI/CD, Static Analysis, Browser Tests

- Add GitHub Actions CI workflow (.github/workflows/ci.yml)
  - Laravel Pint code style check
  - PHPStan static analysis (level 5)
  - Test suite with parallel execution
  - Dusk browser tests (disabled by default)
- Add phpstan.neon config (level 5, ignores User notifications methods)
- Add Dusk browser tests (ProjectWorkflowTest)
- Install laravel/dusk + chromedriver

Tests: 101 passing (319 assertions)

tests/Browser/ExampleTest.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Tests\Browser;
+
+use Illuminate\Foundation\Testing\DatabaseMigrations;
+use Laravel\Dusk\Browser;
+use Tests\DuskTestCase;
+
+class ExampleTest extends DuskTestCase
+{
+    /**
+     * A basic browser test example.
+     */
+    public function test_basic_example(): void
+    {
+        $this->browse(function (Browser $browser) {
+            $browser->visit('/')
+                ->assertSee('Laravel');
+        });
+    }
+}