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/SourceLocation.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace SourceSpan;
+
+use League\Uri\Contracts\UriInterface;
+
+interface SourceLocation
+{
+    public function getOffset(): int;
+
+    /**
+     * The 0-based line of that location
+     */
+    public function getLine(): int;
+
+    /**
+     * The 0-based column of that location
+     */
+    public function getColumn(): int;
+
+    public function getSourceUrl(): ?UriInterface;
+
+    /**
+     * Returns the distance in characters between $this and $other.
+     *
+     * This always returns a non-negative value.
+     *
+     * @return int<0, max>
+     */
+    public function distance(SourceLocation $other): int;
+
+    /**
+     * Returns a span that covers only a single point: this location.
+     */
+    public function pointSpan(): SourceSpan;
+
+    /**
+     * Compares two locations.
+     *
+     * It returns a negative integer if $this is ordered before $other,
+     * a positive integer if $this is ordered after $other,
+     * and zero if $this and $other are ordered together.
+     *
+     * $other must have the same source URL as $this.
+     */
+    public function compareTo(SourceLocation $other): int;
+}