CMS 2.0 - Theme engine, logging, admin improvements

Major changes:
- New ThemeManager with Twig templating and SCSS compilation
- Dynamic themes system (themes/default, themes/demo)
- LogManager with SQLite storage and syslog forwarding
- RequestLogger with static helper methods
- Admin UI overhaul (Bootstrap 5, dark mode)
- Admin config page with logging and theme settings
- Admin logs page with filters and search
- Removed legacy Mustache templates
- Removed test plugin and theme
- Composer dependencies: Twig, scssphp, CommonMark, MaxMind GeoIP

vendor/scssphp/source-span/src/Highlighter/Line.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace SourceSpan\Highlighter;
+
+/**
+ * A single line of the source file being highlighted.
+ *
+ * @internal
+ */
+final class Line
+{
+    /**
+     * All highlights that cover any portion of this line, in source span order.
+     *
+     * This is populated after the initial line is created.
+     *
+     * @var list<Highlight>
+     */
+    public array $highlights = [];
+
+    /**
+     * The URL of the source file in which this line appears.
+     *
+     * For lines created from spans without an explicit URL, this is an opaque
+     * object that differs between lines that come from different spans.
+     */
+    public readonly object $url;
+
+
+    /**
+     * @param int $number The O-based line number in the source file
+     */
+    public function __construct(
+        public readonly string $text,
+        public readonly int $number,
+        object $url,
+    ) {
+        $this->url = $url;
+    }
+}