refactor: split project into web and server directories

- Move frontend to web/ directory
- Add server/ directory for backend
- Restructure project for前后端分离架构

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

@@ -1,5 +1,9 @@
 node_modules/
 dist/
+.vite/
+web/node_modules/
+web/dist/
+web/.vite/
 .omc/
 .omx/
 .claude/