feat(ai): add SUPERVISOR_LOGFILE env var to supervisor-ui for RunPod logs

Configure supervisor-ui to use correct logfile path (/workspace/logs/supervisord.log)
for RunPod Supervisor instance. Fixes logs page error on https://supervisor.ai.pivoine.art/logs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

ai/compose.yaml

@@ -246,6 +246,7 @@ services:
       # Connect to RunPod Supervisor via Tailscale
       SUPERVISOR_HOST: ${GPU_TAILSCALE_IP}
       SUPERVISOR_PORT: ${SUPERVISOR_BACKEND_PORT:-9001}
+      SUPERVISOR_LOGFILE: /workspace/logs/supervisord.log
       # No auth needed - Supervisor has auth disabled (protected by Authelia)
     networks:
       - compose_network