fix: P0遗留修复 + ADR/SOP文档

- requirements.txt: 添加 passlib[bcrypt] 依赖
- deploy-server/nginx.conf: /ws/ 路径添加 access_log off
- docs/ADRs/: 新增 4 个 ADR 决策记录
- docs/SOPs/: 新增 4 个 SOP 操作规程

deploy-server/nginx/nginx.conf

@@ -165,6 +165,7 @@ http {
         # WebSocket — /ws/（坐席端实时通信）
         # ------------------------------------------------------------------
         location /ws/ {
+            access_log off;  # P0-#4: 关闭 WS 路径日志，避免 token 泄露
             proxy_pass http://backend_api;
             proxy_http_version 1.1;
             proxy_set_header Upgrade $http_upgrade;