fix: Correct Nginx proxy port configuration (5001, not 5004)

DISCOVERY:
- Nginx was incorrectly set to port 5004 (app server)
- Correct setting is port 5001 (TaxBaik.Proxy)
- Proxy reads taxbaik_port file and auto-routes to active port

ARCHITECTURE:
Nginx (5001) → TaxBaik.Proxy (5001) → Active Port (5003/5004)

FIX:
- Added validation in CI workflow to check Nginx config
- Manual intervention note for operators
- Will prevent 404 errors on next deployment

IMMEDIATE ACTION REQUIRED:
Server operator must run on 178.104.200.7:
  sudo sed -i 's|proxy_pass         http://127.0.0.1:500[34];|proxy_pass         http://127.0.0.1:5001;|g' /etc/nginx/sites-available/default
  sudo nginx -t && sudo systemctl reload nginx

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

.gitea/workflows/deploy.yml

@@ -193,19 +193,12 @@ jobs:
           chmod +x "\$DEPLOY_DIR/deploy_gb.sh"
           "\$DEPLOY_DIR/deploy_gb.sh" "\$DEPLOY_DIR"
 
-          echo "--- [4.5/5] Nginx 설정 업데이트 (root 권한) ---"
-          TARGET_PORT=\$(cat \$DEPLOY_HOME/taxbaik_port | tr -d '[:space:]')
-          cat > /tmp/update_nginx.sh << 'NGINX_UPDATE'
-#!/bin/bash
-TARGET_PORT=\$1
-sed -i "s|proxy_pass.*http://127.0.0.1:500[34];|proxy_pass         http://127.0.0.1:\${TARGET_PORT};|g" /etc/nginx/sites-available/default
-nginx -t || { echo "❌ Nginx syntax error" >&2; exit 1; }
-systemctl reload nginx
-echo "✓ Nginx reloaded with port \${TARGET_PORT}"
-NGINX_UPDATE
-          chmod +x /tmp/update_nginx.sh
-          sudo /tmp/update_nginx.sh "\${TARGET_PORT}" || { echo "⚠️ Nginx update requires sudo privileges (expected in CI)" >&2; }
-          rm -f /tmp/update_nginx.sh
+          echo "--- [4.5/5] Nginx 설정 검증 ---"
+          # Nginx는 항상 포트 5001 (TaxBaik.Proxy)을 가리켜야 함
+          # 프록시가 taxbaik_port 파일을 읽어서 자동으로 라우팅
+          EXPECTED_PROXY="http://127.0.0.1:5001;"
+          grep "proxy_pass.*5001" /etc/nginx/sites-available/default > /dev/null 2>&1 || \
+            echo "⚠️ Warning: Nginx may not be configured for port 5001 (TaxBaik.Proxy). Manual intervention may be needed."
 
           echo "--- [5/5] 헬스 체크 (최대 60초) ---"
           ATTEMPTS=20