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/phpunit/php-code-coverage/src/Util/Filesystem.php

@@ -0,0 +1,37 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of phpunit/php-code-coverage.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace SebastianBergmann\CodeCoverage\Util;
+
+use function is_dir;
+use function mkdir;
+use function sprintf;
+
+/**
+ * @internal This class is not covered by the backward compatibility promise for phpunit/php-code-coverage
+ */
+final class Filesystem
+{
+    /**
+     * @throws DirectoryCouldNotBeCreatedException
+     */
+    public static function createDirectory(string $directory): void
+    {
+        $success = !(!is_dir($directory) && !@mkdir($directory, 0777, true) && !is_dir($directory));
+
+        if (!$success) {
+            throw new DirectoryCouldNotBeCreatedException(
+                sprintf(
+                    'Directory "%s" could not be created',
+                    $directory
+                )
+            );
+        }
+    }
+}

vendor/phpunit/php-code-coverage/src/Util/Percentage.php

@@ -0,0 +1,66 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of phpunit/php-code-coverage.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace SebastianBergmann\CodeCoverage\Util;
+
+use function sprintf;
+
+/**
+ * @internal This class is not covered by the backward compatibility promise for phpunit/php-code-coverage
+ */
+final class Percentage
+{
+    /**
+     * @var float
+     */
+    private $fraction;
+
+    /**
+     * @var float
+     */
+    private $total;
+
+    public static function fromFractionAndTotal(float $fraction, float $total): self
+    {
+        return new self($fraction, $total);
+    }
+
+    private function __construct(float $fraction, float $total)
+    {
+        $this->fraction = $fraction;
+        $this->total    = $total;
+    }
+
+    public function asFloat(): float
+    {
+        if ($this->total > 0) {
+            return ($this->fraction / $this->total) * 100;
+        }
+
+        return 100.0;
+    }
+
+    public function asString(): string
+    {
+        if ($this->total > 0) {
+            return sprintf('%01.2F%%', $this->asFloat());
+        }
+
+        return '';
+    }
+
+    public function asFixedWidthString(): string
+    {
+        if ($this->total > 0) {
+            return sprintf('%6.2F%%', $this->asFloat());
+        }
+
+        return '';
+    }
+}