fix(deploy): SSH 호스트를 내부 IP(192.168.1.20)로 고정

signal-batch 프로젝트 패턴과 동일하게 호스트 실제 내부 IP 사용.
Docker gateway 감지 방식(ip route, /proc/net/route) 모두 불안정하여 제거.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/deploy.yml

@@ -85,15 +85,14 @@ jobs:
       - name: Restart backend via SSH
         env:
           DEPLOY_KEY: ${{ secrets.DEPLOY_SSH_KEY }}
+          DEPLOY_HOST: 192.168.1.20
         run: |
           mkdir -p ~/.ssh
           echo "$DEPLOY_KEY" > ~/.ssh/id_deploy
           chmod 600 ~/.ssh/id_deploy
-          # Docker 컨테이너 → 호스트: default gateway (최소 의존)
-          DOCKER_HOST_IP=$(cat /proc/net/route | awk '$2 == "00000000" {printf "%d.%d.%d.%d", "0x"substr($3,7,2), "0x"substr($3,5,2), "0x"substr($3,3,2), "0x"substr($3,1,2); exit}')
-          ssh-keyscan $DOCKER_HOST_IP >> ~/.ssh/known_hosts 2>/dev/null || true
+          ssh-keyscan $DEPLOY_HOST >> ~/.ssh/known_hosts 2>/dev/null || true
 
-          SSH_CMD="ssh -i ~/.ssh/id_deploy -o StrictHostKeyChecking=no root@$DOCKER_HOST_IP"
+          SSH_CMD="ssh -i ~/.ssh/id_deploy -o StrictHostKeyChecking=no root@$DEPLOY_HOST"
 
           $SSH_CMD bash -s << 'RESTART'
           set -e