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/tests/ParseResult/AppendTest.php

@@ -0,0 +1,53 @@
+<?php declare(strict_types=1);
+/**
+ * This file is part of the Parsica library.
+ *
+ * Copyright (c) 2020 Mathias Verraes <mathias@verraes.net>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Tests\Parsica\Parsica\ParseResult;
+
+use PHPUnit\Framework\TestCase;
+use Parsica\Parsica\Internal\Fail;
+use Parsica\Parsica\Internal\Succeed;
+use Parsica\Parsica\PHPUnit\ParserAssertions;
+use Parsica\Parsica\StringStream;
+
+final class AppendTest extends TestCase
+{
+    use ParserAssertions;
+
+    /** @test */
+    public function append_strings()
+    {
+        $remainder = new StringStream("");
+        $succeed1 = new Succeed("Parsed1", new StringStream("Remain1"));
+        $succeed2 = new Succeed("Parsed2", new StringStream("Remain2"));
+        $fail1 = new Fail("Expected1", new StringStream("Got1"));
+        $fail2 = new Fail("Expected2", new StringStream("Got2"));
+
+        $this->assertStrictlyEquals(new Succeed("Parsed1Parsed2", new StringStream("Remain2")), $succeed1->append($succeed2));
+        $this->assertStrictlyEquals(new Fail("Expected1", new StringStream("Got1")), $succeed1->append($fail1));
+        $this->assertStrictlyEquals(new Fail("Expected1", new StringStream("Got1")), $fail1->append($succeed2));
+        $this->assertStrictlyEquals(new Fail("Expected1", new StringStream("Got1")), $fail1->append($fail2));
+    }
+    /** @test */
+    public function append_with_null()
+    {
+        $null1 = new Succeed(null, new StringStream("Remain Null 1"));
+        $null2 = new Succeed(null, new StringStream("Remain Null 2"));
+        $string = new Succeed("String", new StringStream("Remain String"));
+
+        $first = $string->append($null1);
+        $this->assertStrictlyEquals(new Succeed("String", new StringStream("Remain Null 1")), $first);
+
+        $second = $null1->append($string);
+        $this->assertStrictlyEquals(new Succeed("String", new StringStream("Remain String")), $second);
+
+        $both = $null1->append($null2);
+        $this->assertStrictlyEquals(new Succeed(null, new StringStream("Remain Null 2")), $both);
+    }
+}