Controller v0.7.2: notification preferences sync to hub

- SyncPreferences() method on Notifier: POST to hub /api/v1/preferences
- IsEnabled() getter for hub connectivity check
- settingsNotificationsHandler: sync to hub after local save (3 flash message variants)
- Startup sync: non-blocking goroutine pushes prefs to hub on boot (DB rebuild recovery)
- Updated CONTEXT.md, README.md with v0.7.2 changes

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

controller/README.md

@@ -24,7 +24,7 @@ controller generates secrets, saves app.yaml, runs `docker compose up -d`, and t
 with Traefik routing and health checks. The dashboard correctly shows real-time container states
 including health substatus (starting → healthy → running).
 
-Current version: **v0.6.1**
+Current version: **v0.7.2**
 
 ### What works
 - Dashboard with live container state (green/orange/yellow/red)
@@ -59,6 +59,8 @@ Current version: **v0.6.1**
 - Heartbeat ping (5-minute "I'm alive" signal to Healthchecks)
 - Weekly backup integrity check (restic check, Sunday 04:00)
 - Central hub reporting (periodic JSON push to felhom-hub service)
+- Notification preferences sync to hub (controller → hub on save + startup)
+- Notification system with email delivery via Resend API (hub relay)
 
 ### Known issues / next priorities
 - Cloudflare Tunnel + Traefik TLS: paperless.demo-felhom.eu works locally but shows "Not secure" (certificate chain not fully validated through tunnel)
@@ -133,6 +135,8 @@ controller/
 │   │   ├── collector.go             # Background collector (60s interval, system + docker stats)
 │   │   ├── types.go                 # SystemSample, ContainerSample, StaticSystemInfo structs
 │   │   └── sysinfo.go              # Host-level static info (/proc, /etc)
+│   ├── notify/
+│   │   └── notifier.go              # Notification relay (hub → email), preferences sync, cooldowns
 │   ├── report/
 │   │   ├── types.go                 # Hub report JSON payload definitions
 │   │   ├── builder.go               # Builds report from system/stacks/backup/metrics state
@@ -173,6 +177,7 @@ controller/
 | **Scheduler** | `internal/scheduler/` | ✅ Done | Central job scheduler (periodic + daily, skip-if-running) |
 | **Monitor** | `internal/monitor/` | ✅ Done | Healthchecks.io pings, system health checks |
 | **Metrics** | `internal/metrics/` | ✅ Done | SQLite time-series store, system + container collection |
+| **Notify** | `internal/notify/` | ✅ Done | Notification relay to hub, preferences sync, cooldown tracking |
 | **Report** | `internal/report/` | ✅ Done | Central hub push (JSON report builder + HTTP pusher) |
 | **Backup** | `internal/backup/` | ✅ Done | DB auto-discovery + dump, restic snapshots, prune, manual trigger |
 
@@ -463,7 +468,8 @@ docker compose up -d
 - [x] Heartbeat ping (5-minute "I'm alive" signal)
 - [x] SQLite metrics store (system + container metrics, 60s collection, 30-day prune)
 - [x] Backup integrity check (weekly restic check with Healthchecks ping)
-- [ ] Customer notifications (email/Telegram)
+- [x] Customer notifications (email via hub relay + Resend API)
+- [x] Notification preferences sync (controller → hub on save + startup)
 
 ### Phase 3 — Backups ✅ COMPLETE
 - [x] DB auto-discovery (PostgreSQL/MariaDB containers via docker inspect)
@@ -496,7 +502,9 @@ docker compose up -d
 - [x] Hub service (felhom-hub: REST API + SQLite + dark-theme dashboard)
 - [x] K8s manifests for hub deployment on k3s
 - [ ] Fleet-wide update management
-- [ ] Customer notifications (email/Telegram)
+- [x] Customer notifications (email via hub relay)
+- [x] Notification preferences sync (controller → hub)
+- [x] Hub customer detail page: notification preferences + log display
 
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