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/dotenv/Exception/ExceptionInterface.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Dotenv\Exception;
+
+/**
+ * Interface for exceptions.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+interface ExceptionInterface extends \Throwable
+{
+}

vendor/symfony/dotenv/Exception/FormatException.php

@@ -0,0 +1,34 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Dotenv\Exception;
+
+/**
+ * Thrown when a file has a syntax error.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+final class FormatException extends \LogicException implements ExceptionInterface
+{
+    private FormatExceptionContext $context;
+
+    public function __construct(string $message, FormatExceptionContext $context, int $code = 0, ?\Throwable $previous = null)
+    {
+        $this->context = $context;
+
+        parent::__construct(\sprintf("%s in \"%s\" at line %d.\n%s", $message, $context->getPath(), $context->getLineno(), $context->getDetails()), $code, $previous);
+    }
+
+    public function getContext(): FormatExceptionContext
+    {
+        return $this->context;
+    }
+}

vendor/symfony/dotenv/Exception/FormatExceptionContext.php

@@ -0,0 +1,49 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Dotenv\Exception;
+
+/**
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+final class FormatExceptionContext
+{
+    private string $data;
+    private string $path;
+    private int $lineno;
+    private int $cursor;
+
+    public function __construct(string $data, string $path, int $lineno, int $cursor)
+    {
+        $this->data = $data;
+        $this->path = $path;
+        $this->lineno = $lineno;
+        $this->cursor = $cursor;
+    }
+
+    public function getPath(): string
+    {
+        return $this->path;
+    }
+
+    public function getLineno(): int
+    {
+        return $this->lineno;
+    }
+
+    public function getDetails(): string
+    {
+        $before = str_replace("\n", '\n', substr($this->data, max(0, $this->cursor - 20), min(20, $this->cursor)));
+        $after = str_replace("\n", '\n', substr($this->data, $this->cursor, 20));
+
+        return '...'.$before.$after."...\n".str_repeat(' ', \strlen($before) + 2).'^ line '.$this->lineno.' offset '.$this->cursor;
+    }
+}

vendor/symfony/dotenv/Exception/PathException.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Dotenv\Exception;
+
+/**
+ * Thrown when a file does not exist or is not readable.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+final class PathException extends \RuntimeException implements ExceptionInterface
+{
+    public function __construct(string $path, int $code = 0, ?\Throwable $previous = null)
+    {
+        parent::__construct(\sprintf('Unable to read the "%s" environment file.', $path), $code, $previous);
+    }
+}

vendor/symfony/dotenv/Exception/VariableCircularReferenceException.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Dotenv\Exception;
+
+/**
+ * Thrown when there are too many levels of variable indirection in env vars.
+ *
+ * @author Pascal CESCON <pascal.cescon@gmail.com>
+ */
+final class VariableCircularReferenceException extends \LogicException implements ExceptionInterface
+{
+}