refactor: Cleanup git state - commit all staged changes

Major refactoring cleanup:
- Add new controller architecture (class-controller-*.php)
- Add new settings-v2 UI (views/settings-v2/)
- Add new CSS architecture (agentic-sidebar.css, tokens)
- Add esbuild build pipeline (scripts/build.js, package.json)
- Add composer dependencies (vendor/)
- Add frontend src directory (assets/js/src/index.jsx)
- Add documentation files
- Remove old/obsolete files (class-settings.php, old CSS)

This commits all pending changes from previous refactoring efforts.

tests/README.md

@@ -0,0 +1,40 @@
+# Unit Tests
+
+## Setup
+
+```bash
+# Install dependencies
+composer install
+
+# Run all tests
+./vendor/bin/phpunit
+
+# Run specific test file
+./vendor/bin/phpunit tests/test-model-registry.php
+
+# Run with testdox output
+./vendor/bin/phpunit --testdox
+
+# Generate coverage report
+./vendor/bin/phpunit --testdox --coverage-html coverage
+```
+
+## Test Structure
+
+| File | Class Under Test | Coverage |
+|------|-----------------|----------|
+| `test-model-registry.php` | `WPAW_Model_Registry` | Model defaults, validation, display names |
+
+## Adding Tests
+
+1. Create a new file in `tests/` with the naming convention `test-{class-name}.php`
+2. Class name should be `Test_{ClassName}` extending `PHPUnit\Framework\TestCase`
+3. Add the class require to `tests/bootstrap.php` if the class is not autoloaded
+4. Run tests to verify
+
+## Running Without Composer
+
+If PHPUnit is installed globally:
+```bash
+phpunit --bootstrap tests/bootstrap.php tests/
+```