Remove ping_uuids from example config, update architecture diagram

- Comment out ping_uuids section in controller.yaml.example (deprecated)
- Architecture diagram: remove status.felhom.eu, update to Hub event system
- Mark Healthchecks references as deprecated throughout README

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

controller/README.md

@@ -49,19 +49,19 @@ A single, lightweight Go container that replaces Portainer + scattered systemd s
 │  │ App      │   │  └──────────┘  └─────────────────────────┘│  │
 │  │ stacks   │   │  ┌──────────┐  ┌─────────────────────────┐│  │
 │  │ (docker  │   │  │Scheduler │  │ Monitor & Metrics       ││  │
-│  │ compose) │   │  │(cron-like│  │ (health, pings, SQLite  ││  │
+│  │ compose) │   │  │(cron-like│  │ (health, SQLite         ││  │
 │  └──────────┘   │  │  jobs)   │  │  time-series, Chart.js) ││  │
 │                 │  └──────────┘  └─────────────────────────┘│  │
 │                 │  ┌──────────┐  ┌─────────────────────────┐│  │
 │                 │  │ Notify   │  │ REST API + Hub Reporter ││  │
-│                 │  │ (email)  │  │ (JSON push to hub)      ││  │
+│                 │  │ (events) │  │ (JSON push + events)    ││  │
 │                 │  └──────────┘  └─────────────────────────┘│  │
 │                 └────────────────────────────────────────────┘  │
 └─────────────────────────────────────────────────────────────────┘
-         │ pings              │ JSON push          │ git pull
-         ▼                    ▼                    ▼
-  status.felhom.eu      hub.felhom.eu       gitea.dooplex.hu
-  (Healthchecks)        (central dashboard)  (stack definitions)
+         │ events + reports      │ git pull
+         ▼                       ▼
+   hub.felhom.eu           gitea.dooplex.hu
+   (central dashboard)     (stack definitions)
 ```
 
 ### Key Architecture Decisions
@@ -85,7 +85,7 @@ A single, lightweight Go container that replaces Portainer + scattered systemd s
 | **Backup** | `internal/backup/` | Per-drive 3-layer backup: DB dumps → restic snapshots → cross-drive copies, restore |
 | **Storage** | `internal/storage/` | Disk scanning (`lsblk`), partitioning (`sfdisk`), formatting (`mkfs.ext4`), mounting, data migration (`rsync`) |
 | **System** | `internal/system/` | System info (`/proc`), CPU collector, mount points, disk usage, FS info |
-| **Monitor** | `internal/monitor/` | Healthchecks.io pinger, system health checks, storage watchdog |
+| **Monitor** | `internal/monitor/` | System health checks, storage watchdog, legacy Healthchecks pinger (deprecated) |
 | **Metrics** | `internal/metrics/` | SQLite time-series store, system + container metric collection |
 | **Scheduler** | `internal/scheduler/` | Central job scheduler (periodic + daily, skip-if-running, panic recovery) |
 | **SelfUpdate** | `internal/selfupdate/` | Version checking (registry), update trigger, state persistence, startup verification |
@@ -624,7 +624,7 @@ The controller can update itself — a Watchtower-style pull-and-restart mechani
 
 ##### Design Philosophy
 
-- **No automatic rollback** — follows the Watchtower pattern (24k+ GitHub stars, no rollback). Docker's `restart: unless-stopped` policy is the crash safety net. Healthchecks.io detects when the controller goes down.
+- **No automatic rollback** — follows the Watchtower pattern (24k+ GitHub stars, no rollback). Docker's `restart: unless-stopped` policy is the crash safety net. The Hub's dead man's switch detects when the controller goes down.
 - **Audit state file** — `update-state.json` in the data volume records every update attempt (previous version, target version, initiator, result). Operators can SSH in and revert using `PreviousImage` from this file.
 - **Backup-aware** — refuses to start an update while a backup is in progress (`backupRunning()` guard).
 
@@ -980,7 +980,7 @@ Auto-generated during deployment. Contains env vars, locked fields list, deploy
 |-----|------|------|---------|
 | status-refresh | periodic | 30s | Refresh container states |
 | stack-scan | periodic | 2m | Rescan stacks directory |
-| heartbeat | periodic | 5m | Ping Healthchecks "I'm alive" |
+| heartbeat | periodic | 5m | Legacy Healthchecks ping (deprecated — Hub handles via event system) |
 | system-health | periodic | configurable | Health checks + alert refresh |
 | backup-cache | periodic | 5m | Refresh backup status cache |
 | hub-report | periodic | 15m | Push report to central hub |