refactor: rename stock-lab → stock (graduation)

- git mv stock-lab/ → stock/
- docker-compose.yml: 서비스 키 + container_name + build.context +
  frontend.depends_on + agent-office STOCK_LAB_URL → STOCK_URL
- agent-office/app: config.py, service_proxy.py, agents/stock.py, tests/
  STOCK_LAB_URL → STOCK_URL
- nginx/default.conf: proxy_pass http://stock-lab → http://stock (3 lines)
- CLAUDE.md / README.md / STATUS.md / scripts/ 문구 갱신
- stock/ 내부 자기 참조 갱신

lab 네이밍 정책 (feedback_lab_naming.md) graduation.
API URL / Python import / DB 파일명 변경 없음.

nginx/default.conf

@@ -139,17 +139,17 @@ server {
 	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_pass http://stock-lab:8000/api/stock/;
+	proxy_pass http://stock:8000/api/stock/;
   }
   
-  # trade API (Stock Lab Proxy)
+  # trade API (Stock Proxy)
   location /api/trade/ {
 	proxy_http_version 1.1;
 	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_pass http://stock-lab:8000/api/trade/;
+	proxy_pass http://stock:8000/api/trade/;
   }
 
   # blog-marketing API
@@ -166,14 +166,14 @@ server {
     proxy_pass http://$blog_backend$request_uri;
   }
 
-  # portfolio API (Stock Lab) — trailing slash 유무 모두 매칭
+  # portfolio API (Stock) — trailing slash 유무 모두 매칭
   location /api/portfolio {
 	proxy_http_version 1.1;
 	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_pass http://stock-lab:8000/api/portfolio;
+	proxy_pass http://stock:8000/api/portfolio;
   }