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

frontend/Dockerfile

@@ -0,0 +1,13 @@
+# QuantDinger Frontend - Pre-built Static Files
+# No build step needed - dist/ is already compiled.
+FROM nginx:1.25-alpine
+
+# Copy pre-built frontend files
+COPY dist/ /usr/share/nginx/html/
+
+# Copy nginx configuration
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+EXPOSE 80
+
+CMD ["nginx", "-g", "daemon off;"]

frontend/VERSION

@@ -0,0 +1 @@
+2.2.1

frontend/nginx.conf

@@ -0,0 +1,54 @@
+server {
+    listen 80;
+    server_name localhost;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # Security headers
+    add_header X-Frame-Options "SAMEORIGIN" always;
+    add_header X-Content-Type-Options "nosniff" always;
+    add_header X-XSS-Protection "1; mode=block" always;
+
+    # Gzip compression
+    gzip on;
+    gzip_vary on;
+    gzip_min_length 1000;
+    gzip_comp_level 6;
+    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript image/svg+xml;
+
+    # Static asset caching (hashed filenames = immutable)
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot|map)$ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+        access_log off;
+    }
+
+    # API proxy to backend
+    location /api/ {
+        proxy_pass http://backend:5000/api/;
+        proxy_http_version 1.1;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection 'upgrade';
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_cache_bypass $http_upgrade;
+        proxy_read_timeout 300s;
+        proxy_connect_timeout 75s;
+        # Allow large file uploads (e.g. indicator import)
+        client_max_body_size 10m;
+    }
+
+    # SPA routing support (all routes fall back to index.html)
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # Health check endpoint
+    location /health {
+        return 200 'OK';
+        add_header Content-Type text/plain;
+        access_log off;
+    }
+}