feat: UAT environment setup with separate PocketBase instance

- Add UAT PocketBase on port 8712 with separate pb_data_uat
- Add UAT nginx config proxying to UAT PB (port 8712)
- Update Dockerfile to support NGINX_CONF build arg
- Add .gitignore for .playwright-mcp/
- Auto-generated team_sessions migration

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

frontend/Dockerfile

@@ -22,8 +22,9 @@ FROM nginx:alpine
 # 复制构建产物
 COPY --from=builder /app/dist /usr/share/nginx/html
 
-# 复制 nginx 配置
-COPY nginx.conf /etc/nginx/conf.d/default.conf
+# 通过 NGINX_CONF 参数选择配置文件（默认 dev）
+ARG NGINX_CONF=nginx.conf
+COPY ${NGINX_CONF} /etc/nginx/conf.d/default.conf
 
 EXPOSE 80