Switch production deployment from Docker to PM2 on Ubuntu.

Add Express gateway, ecosystem config, and one-click install with native PostgreSQL, Node, and Python venv on port 23566.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/Dockerfile

@@ -1,11 +0,0 @@
-FROM node:20-alpine AS build
-WORKDIR /app
-COPY package*.json ./
-RUN npm ci
-COPY . .
-RUN npm run build
-
-FROM nginx:alpine
-COPY nginx.conf /etc/nginx/conf.d/default.conf
-COPY --from=build /app/dist /usr/share/nginx/html
-EXPOSE 80

frontend/nginx.conf

@@ -1,17 +0,0 @@
-server {
-    listen 80;
-    server_name localhost;
-    root /usr/share/nginx/html;
-    index index.html;
-
-    location /api/ {
-        proxy_pass http://api:8000/api/;
-        proxy_set_header Host $host;
-        proxy_set_header X-Real-IP $remote_addr;
-        client_max_body_size 10M;
-    }
-
-    location / {
-        try_files $uri $uri/ /index.html;
-    }
-}