chore: Deployment version naming and cleanup policy

- **Version naming**: Include date, time, commit hash, and CI run number
  Format: quantengine_YYYYMMDD_HHMMSS_COMMIT_HASH_RUNNUM
- **Cleanup script**: Auto-remove old versions to prevent disk exhaustion
  - Keep 5 most recent by default
  - Remove staging/test versions
  - Can be run weekly via cron or after deployments
  - Supports dry-run mode for validation

Addresses: Disk usage management for long-running CI/CD pipeline

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

.gitea/workflows/deploy-prod.yml

@@ -182,9 +182,11 @@ jobs:
           set -e
           TIMESTAMP=$(date +%Y%m%d_%H%M%S)
           COMMIT=$(git rev-parse --short HEAD)
+          RUN_NUM="${{ github.run_number }}"
           DEPLOY_BASE="/home/kjh2064/deployments"
           ACTIVE_LINK="/home/kjh2064/quantengine_active"
-          TARGET_DIR="${DEPLOY_BASE}/quantengine_${TIMESTAMP}"
+          # Version format: quantengine_YYYYMMDD_HHMMSS_COMMIT_HASH_RUNNUM
+          TARGET_DIR="${DEPLOY_BASE}/quantengine_${TIMESTAMP}_${COMMIT}_${RUN_NUM}"
 
           TELEGRAM_BOT_TOKEN="${{ secrets.TELEGRAM_BOT_TOKEN }}"
           [ -z "$TELEGRAM_BOT_TOKEN" ] && TELEGRAM_BOT_TOKEN="${{ env.TELEGRAM_BOT_TOKEN_DEFAULT }}"