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.

vendor/symfony/contracts/splitsh.json

@@ -0,0 +1,13 @@
+{
+    "subtrees": {
+        "cache-contracts": "Cache",
+        "deprecation-contracts": "Deprecation",
+        "event-dispatcher-contracts": "EventDispatcher",
+        "http-client-contracts": "HttpClient",
+        "service-contracts": "Service",
+        "translation-contracts": "Translation"
+    },
+    "defaults": {
+        "git_constraint": "<1.8.2"
+    }
+}