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.

package.json

@@ -0,0 +1,13 @@
+{
+  "name": "wp-agentic-writer",
+  "version": "1.0.0",
+  "description": "WP Agentic Writer - AI-powered content generation for WordPress",
+  "scripts": {
+    "build": "node scripts/build.js",
+    "build:watch": "node scripts/build.js --watch",
+    "dev": "npm run build"
+  },
+  "devDependencies": {
+    "esbuild": "^0.20.0"
+  }
+}