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/league/csv/src/Warning.php

@@ -0,0 +1,87 @@
+<?php
+
+/**
+ * League.Csv (https://csv.thephpleague.com)
+ *
+ * (c) Ignace Nyamagana Butera <nyamsprod@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace League\Csv;
+
+use ErrorException;
+use Throwable;
+
+use function in_array;
+use function restore_error_handler;
+use function set_error_handler;
+
+use const E_USER_WARNING;
+use const E_WARNING;
+
+/**
+ * @internal Utility class to wrap callbacks to control emitted warnings during their execution.
+ *
+ * @template TReturn
+ */
+final class Warning
+{
+    /**
+     * Converts PHP Warning into ErrorException.
+     *
+     * @param mixed ...$arguments the callback arguments if needed
+     *
+     * @throws ErrorException If the callback internally emits a Warning
+     * @throws Throwable on callback execution if the callback throws
+     *
+     * @return TReturn The result returned by the callback.
+     */
+    public static function trap(callable $callback, mixed ...$arguments): mixed
+    {
+        set_error_handler(
+            fn (int $errno, string $errstr, string $errfile, int $errline): bool =>
+            in_array($errno, [E_WARNING, E_USER_WARNING], true)
+                ? throw new ErrorException($errstr, 0, $errno, $errfile, $errline)
+                : false
+        );
+
+        return self::execute($callback, $arguments);
+    }
+
+    /**
+     * Hides PHP Warnings.
+     *
+     * @param mixed ...$arguments the callback arguments if needed
+     *
+     * @throws Throwable on callback execution if the callback throws
+     *
+     * @return TReturn The result returned by the callback.
+     */
+    public static function cloak(callable $callback, mixed ...$arguments): mixed
+    {
+        set_error_handler(
+            fn (int $errno, string $errstr, string $errfile, int $errline): bool =>
+            in_array($errno, [E_WARNING, E_USER_WARNING], true),
+        );
+
+        return self::execute($callback, $arguments);
+    }
+
+    /**
+     * @param array<mixed> $arguments the callback arguments if needed
+     *
+     * @return TReturn The result returned by the callback.
+     */
+    private static function execute(callable $callback, array $arguments)
+    {
+        try {
+            return $callback(...$arguments);
+        } finally {
+            restore_error_handler();
+        }
+    }
+}