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/parsica-php/parsica/docs/installation.md

@@ -0,0 +1,67 @@
+---
+title: Installation & Requirements
+---
+
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+<Tabs
+  defaultValue="cli"
+  values={[
+    { label: 'Command line', value: 'cli', },
+    { label: 'composer.json', value: 'composer', },
+  ]
+}>
+<TabItem value="cli">
+
+```bash
+composer require parsica-php/parsica
+```
+
+</TabItem>
+<TabItem value="composer">
+
+```json
+"require": {
+    "parsica-php/parsica": "dev-main"
+}
+```
+
+</TabItem>
+
+</Tabs>
+
+
+## Requirements
+
+- PHP 7.4 or higher
+- [The multibyte string extension for PHP (aka mbstring)](https://www.php.net/manual/en/book.mbstring.php)
+
+(@TODO: add polyfill for mbstring).
+
+
+## Usage
+
+In a .php file, make sure the Composer autoloader is included:
+
+`require_once __DIR__.'/../vendor/autoload.php';`
+
+Import parsers and combinators:
+
+`use function Parsica\Parsica\char;`
+
+You can combine multiple imports in one statement: 
+
+`use function Parsica\Parsica\{between, char, atLeastOne, alphaChar};`
+
+Finally, add some code:
+
+```php
+<?php
+$parser = between(char('{'), char('}'), atLeastOne(alphaChar()));
+$result = $parser->tryString("{Hello}");
+echo $result->output();
+// outputs "Hello"
+```
+