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.

composer.json

@@ -0,0 +1,25 @@
+{
+    "name": "wp-agentic-writer/wp-agentic-writer",
+    "description": "AI-powered writing assistant for WordPress Gutenberg",
+    "type": "wordpress-plugin",
+    "require-dev": {
+        "phpunit/phpunit": "^9.6",
+        "phpdocumentor/phpdocumentor": "^3.4",
+        "squizlabs/php_codesniffer": "^3.7"
+    },
+    "autoload": {
+        "psr-4": {
+            "WP_Agentic_Writer\\": "includes/"
+        }
+    },
+    "scripts": {
+        "test": "phpunit",
+        "test-coverage": "phpunit --coverage-html coverage",
+        "cs": "phpcs --standard=PSR12 includes/"
+    },
+    "config": {
+        "allow-plugins": {
+            "dealerdirect/phpcodesniffer-composer-installer": true
+        }
+    }
+}