feat: Add Nanaxe server with Docker, GitHub Actions CI/CD, and auto-deployment

- Add complete server infrastructure with Gitea, API, PostgreSQL
- Implement Obsidian-compatible markdown mindmap converter
- Add Flutter service for server synchronization
- Configure GitHub Actions for automated build and deploy
- Add production docker-compose with health checks
- Include VPS setup and deployment scripts
- Add comprehensive deployment documentation

lib/models/calendar_event_model.dart

@@ -43,8 +43,12 @@ class CalendarEventModel {
 
   factory CalendarEventModel.fromFirestore(DocumentSnapshot doc) {
     final data = doc.data() as Map<String, dynamic>;
+    return CalendarEventModel.fromMap(doc.id, data);
+  }
+
+  factory CalendarEventModel.fromMap(String id, Map<String, dynamic> data) {
     return CalendarEventModel(
-      id: doc.id,
+      id: id,
       title: data['title'] ?? '',
       description: data['description'],
       location: data['location'] ?? '',