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

pubspec.lock

@@ -1008,6 +1008,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.5.0"
+  reactive_mind_map:
+    dependency: "direct main"
+    description:
+      name: reactive_mind_map
+      sha256: ee7a09c48fc3cd593c8539fee8e4229bf26229580aad3ee35a235c1523dabee8
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.2"
   riverpod:
     dependency: transitive
     description: