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/FileLocation.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace SourceSpan;
+
+use League\Uri\Contracts\UriInterface;
+
+/**
+ * The implementation of {@see SourceLocation} based on a {@see SourceFile}.
+ *
+ * @see SourceFile::location()
+ */
+final class FileLocation extends SourceLocationMixin
+{
+    /**
+     * @internal
+     */
+    public function __construct(
+        private readonly SourceFile $file,
+        private readonly int $offset,
+    ) {
+    }
+
+    public function getFile(): SourceFile
+    {
+        return $this->file;
+    }
+
+    public function getOffset(): int
+    {
+        return $this->offset;
+    }
+
+    public function getLine(): int
+    {
+        return $this->file->getLine($this->offset);
+    }
+
+    public function getColumn(): int
+    {
+        return $this->file->getColumn($this->offset);
+    }
+
+    public function getSourceUrl(): ?UriInterface
+    {
+        return $this->file->getSourceUrl();
+    }
+
+    public function pointSpan(): FileSpan
+    {
+        return new ConcreteFileSpan($this->file, $this->offset, $this->offset);
+    }
+}