Initial commit: webtrees full diagram chart module

Interactive SVG family tree visualization using ELK (Sugiyama) for
layout and D3 for rendering. Shows ancestors, descendants, and siblings
in a single diagram with orthogonal bus-line connectors.

Features:
- Bidirectional tree traversal (ancestors + descendants + siblings)
- Generation-aligned layout with post-processing Y-snap
- Person cards with photos, names, dates, and hover bio cards
- "More ancestors" indicator for persons with hidden parents
- Pan/zoom navigation
- Docker dev environment

module.php

@@ -0,0 +1,21 @@
+<?php
+
+/**
+ * Full Diagram module for webtrees.
+ *
+ * @license GPL-3.0-or-later
+ */
+
+declare(strict_types=1);
+
+namespace FullDiagram;
+
+use Composer\Autoload\ClassLoader;
+use Fisharebest\Webtrees\Registry;
+
+// Register PSR-4 autoloader for our namespace
+$loader = new ClassLoader();
+$loader->addPsr4('FullDiagram\\', __DIR__ . '/src');
+$loader->register();
+
+return Registry::container()->get(Module::class);