feat: add group_count metric and status file to health endpoint

[wolffcatskyy]

Summary

• Add group_count field to health endpoint JSON response
• Add HEALTH_STATUS_FILE env var for writing status to a JSON file (for file-based monitors)

Closes #6

New health response

{
  "status": "healthy",
  "version": "1.5.0",
  "uptime_seconds": 3600,
  "crowdsec_connected": true,
  "unifi_connected": true,
  "last_sync_time": 1706500000.123,
  "last_sync_ips": 4521,
  "group_count": 5,
  "last_error": null,
  "memory_mb": 45.2
}

New env var

Variable	Default	Description
HEALTH_STATUS_FILE	(empty)	Path to write status JSON file (e.g., /tmp/bouncer-status.json)

Test plan

• Check /health endpoint includes group_count field
• Set HEALTH_STATUS_FILE=/tmp/bouncer-status.json, verify file is written after sync
• Verify status file contains valid JSON with all metrics
• Without HEALTH_STATUS_FILE set, verify no file is written (no errors)

Generated with Claude Code

[wolffcatskyy]

Closing: this PR modifies bouncer.py which was removed in the v2.0 rewrite (commit 9c124fc). The project has moved from a Python Docker-based bouncer to the native CrowdSec firewall bouncer running directly on UniFi OS with ipset/iptables.

Health endpoint improvements are no longer applicable — the native Go bouncer does not use a Python HTTP health endpoint. Health monitoring in v2.0 is done via systemd service status (systemctl status crowdsec-firewall-bouncer) and ensure-rules.sh cron checks.