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/sebastian/environment/composer.json

@@ -0,0 +1,40 @@
+{
+    "name": "sebastian/environment",
+    "description": "Provides functionality to handle HHVM/PHP environments",
+    "keywords": ["environment","hhvm","xdebug"],
+    "homepage": "http://www.github.com/sebastianbergmann/environment",
+    "license": "BSD-3-Clause",
+    "authors": [
+        {
+            "name": "Sebastian Bergmann",
+            "email": "sebastian@phpunit.de"
+        }
+    ],
+    "config": {
+        "platform": {
+            "php": "7.3.0"
+        },
+        "optimize-autoloader": true,
+        "sort-packages": true
+    },
+    "prefer-stable": true,
+    "require": {
+        "php": ">=7.3"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "^9.3"
+    },
+    "suggest": {
+        "ext-posix": "*"
+    },
+    "autoload": {
+        "classmap": [
+            "src/"
+        ]
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "5.1-dev"
+        }
+    }
+}