Rewrite offline page to use WebAssetManager

- All CSS/JS loading now uses $wa->useStyle/useScript matching index.php
- Added template.offline and template.offline.min to joomla.asset.json
- Font Awesome, Osaka font, themes, user overrides all via WAM

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/joomla.asset.json

@@ -34,6 +34,18 @@
 			"uri": "media/templates/site/mokocassiopeia/css/template.min.css",
 			"attributes": {"media": "all"}
 		},
+		{
+			"name": "template.offline",
+			"type": "style",
+			"uri": "media/templates/site/mokocassiopeia/css/offline.css",
+			"attributes": {"media": "all"}
+		},
+		{
+			"name": "template.offline.min",
+			"type": "style",
+			"uri": "media/templates/site/mokocassiopeia/css/offline.min.css",
+			"attributes": {"media": "all"}
+		},
 		{
 			"name": "template.user",
 			"type": "style",