v2.2.1: frontend closed-source + Docker one-click deploy

- Remove frontend source code (now in private repo)
- Add pre-built frontend/dist/ with Nginx serving
- Simplify docker-compose.yml (no Node.js build needed)
- Update README with docs index and Docker deploy guide
- Add admin order list and AI analysis stats tabs
- Add quick trade API routes
- Clean up redundant files (package-lock.json, yarn.lock, .iml)
- Add GitHub Actions workflow for frontend update automation

quantdinger_vue/.gitignore

@@ -1,21 +0,0 @@
-.DS_Store
-node_modules
-/dist
-# local env files
-.env.local
-.env.*.local
-
-# Log files
-npm-debug.log*
-yarn-debug.log*
-yarn-error.log*
-
-# Editor directories and files
-.idea
-.vscode
-*.suo
-*.ntvs*
-*.njsproj
-*.sln
-*.sw*
-package-lock.json