v0.6.0: healthcheck + hub reporting implementation

- Add heartbeat ping (every 5 min, controller alive signal)
- Add backup integrity check (weekly restic check, Sunday 04:00)
- Add Heartbeat + BackupIntegrity fields to PingUUIDsConfig
- Add HubConfig for central hub reporting
- Add report package (types, builder, pusher) for hub push
- Wire hub reporting into scheduler (configurable interval)
- Update controller.yaml.example with new monitoring + hub sections
- Add monitoring/DEPRECATED.md for legacy bash scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

monitoring/DEPRECATED.md

@@ -0,0 +1,35 @@
+# DEPRECATED — Legacy Monitoring Scripts
+
+> **Superseded by:** felhom-controller v0.4.0+ built-in monitoring
+> **Date:** 2026-02-16
+
+The following scripts in this directory were used for monitoring before the controller
+had built-in health check support. They are **no longer needed** on nodes running
+felhom-controller v0.4.0 or later.
+
+## Replaced scripts
+
+| Legacy script | Replaced by | Controller component |
+|---------------|-------------|---------------------|
+| `backup-healthcheck.sh` | System health scheduler job (every 5 min) | `internal/monitor/healthcheck.go` |
+| `monitoring-setup.sh` | Controller reads `controller.yaml` directly | `internal/config/config.go` |
+| `monitoring.conf.template` | `monitoring` section in `controller.yaml` | `controller.yaml` |
+| `backup-healthcheck.service` | Controller's built-in scheduler | `internal/scheduler/scheduler.go` |
+| `backup-healthcheck.timer` | Controller's built-in scheduler | `internal/scheduler/scheduler.go` |
+
+## What the controller handles natively (v0.6.0+)
+
+- **Heartbeat** ping every 5 minutes (controller process alive)
+- **System health** check every 5 minutes (disk, memory, CPU, temp, Docker, protected containers)
+- **DB dump** ping after daily database dumps
+- **Backup** ping after daily restic snapshots
+- **Backup integrity** check weekly (restic check)
+
+All pings are sent to a Healthchecks.io-compatible server configured in `controller.yaml`.
+Empty or `CHANGEME` UUIDs are silently skipped.
+
+## Do NOT delete these files yet
+
+These scripts are kept for reference in case a customer is still running a pre-controller
+setup. Once all customers are migrated to felhom-controller v0.4.0+, this directory
+can be safely removed.