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/.gitattributes

@@ -1,11 +0,0 @@
-public/* linguist-vendored
-
-# Automatically normalize line endings (to LF) for all text-based files.
-* text=auto eol=lf
-
-# Declare files that will always have CRLF line endings on checkout.
-*.{cmd,[cC][mM][dD]} text eol=crlf
-*.{bat,[bB][aA][tT]} text eol=crlf
-
-# Denote all files that are truly binary and should not be modified.
-*.{ico,png,jpg,jpeg,gif,webp,svg,woff,woff2} binary