v0.9.0: Storage paths registry, per-app HDD_PATH resolution, storage management UI

- Fix backup toggles not appearing (read each app's own HDD_PATH from app.yaml)
- Storage paths registry in settings.json with auto-discovery from deployed apps
- Settings page "Adattárolók" section with disk usage, add/remove/default/schedulable
- Deploy page path field as dropdown of registered storage paths
- Health check storage monitoring (mount point, disk usage alerts)
- Mount-point validation utilities (Linux syscall + cross-platform stubs)
- Controller docker-compose mount changed to /mnt:/mnt:rw for multi-storage

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

CHANGELOG.md

@@ -0,0 +1,99 @@
+# Changelog
+
+## v0.9.0 — Storage Paths Foundation & Backup Toggle Fix (2026-02-17)
+
+### Fixed
+- Per-app backup toggles not appearing on backup page (root cause: missing global `hdd_path` in controller.yaml made `ParseComposeHDDMounts` return nil)
+- Each app's HDD_PATH is now read from its own `app.yaml` env section instead of relying on a global config value
+
+### Added
+- **Storage paths registry** — multiple external storage paths managed in `settings.json` with auto-discovery from deployed apps on startup
+- **Settings page "Adattárolók" section** — view, add, remove, set default, toggle schedulable for storage paths. Disk usage bars, app counts, mount status badges
+- **Deploy page storage dropdown** — `path` field type shows registered schedulable paths as dropdown instead of free-text input
+- **Health check storage monitoring** — checks path accessibility, mount-point validation (warns if data would write to SSD), disk usage alerts at 90%/95%
+- **Mount-point validation** — `IsMountPoint()`, `IsWritable()`, `PathsOverlap()`, `GetDiskUsage()` (Linux via syscall, stubs for other platforms)
+
+### Changed
+- Controller docker-compose mount changed from `${HDD_PATH}:${HDD_PATH}:ro` to `/mnt:/mnt:rw` for multi-storage + restore support
+- `RunHealthCheck()` now accepts storage paths parameter for per-path monitoring
+- `BuildReport()` accepts storage paths for accurate system info in hub reports
+- Removed unused `hddPath` parameter from `DiscoverAppData()` signature
+
+## v0.8.0 — Storage Overview, Per-App Backup Toggles & Limited Restore (2026-02-16)
+
+- Storage overview on backup page (SSD/HDD progress bars + repo stats)
+- Restic password visibility with show/copy for disaster recovery
+- App data discovery (`DiscoverAppData()` with `StackDataProvider` interface)
+- Per-app backup toggles (HDD data paths per app)
+- Dynamic backup paths based on enabled apps
+- Limited app restore from restic snapshots
+- Flash messages on backup page
+
+## v0.7.2 — Fix Notification Preferences Sync (2026-02-16)
+
+- Hub: `POST /api/v1/preferences` endpoint
+- Hub: Notification section on customer detail page
+- Controller: `SyncPreferences` method for hub sync
+- Controller: Sync on settings save + startup
+
+## v0.7.1 — Monitoring Warnings, Dashboard Alerts & Notification System (2026-02-16)
+
+- Monitoring page "Távoli monitoring" section
+- Dashboard alert banners (error/warning/info)
+- Hub notification relay (Resend email)
+- Controller-side notifier with cooldown tracking
+- Notification preferences UI on settings page
+
+## v0.7.0 — Authentication, Persistence & Settings Page (2026-02-16)
+
+- `settings.json` persistence layer
+- Password change via settings page
+- Session management improvements
+- DB validation persistence across restarts
+
+## v0.6.3 — Bug fixes (2026-02-16)
+
+- `--hdd-path` validation in docker-setup.sh
+- `window.event` deprecation fix
+- Page title separator fix
+- `nextPruneLabel()` Sunday fix
+
+## v0.6.0 — Healthcheck + Central Push + Hub Dashboard (2026-02-16)
+
+- Heartbeat + backup integrity pings
+- Central hub reporting (report builder + pusher)
+- Hub service with SQLite store + dark theme dashboard
+
+## v0.5.0 — Monitoring Page with Metrics Store (2026-02-16)
+
+- SQLite metrics store with WAL mode
+- Background metrics collector (60s interval)
+- System + container charts (Chart.js 4.4.7)
+- Per-container detail views
+
+## v0.4.5 — Dedicated Backup Page (2026-02-16)
+
+- Full backup system visibility
+- DB dump engine + restic integration
+- Snapshot history + validation
+- Manual backup trigger
+
+## v0.4.0 — Monitoring & Health + Backups (2026-02-15)
+
+- Central job scheduler
+- CPU/temperature/load monitoring
+- Healthchecks.io integration
+- Database dump + restic backup engine
+
+## v0.3.0 — Templates + Server Split (2026-02-15)
+
+- go:embed template migration
+- Server decomposition (auth, handlers, funcmap)
+- Domain rename (dashboard → felhom)
+
+## v0.2.x — Initial Development (2026-02-13 to 2026-02-15)
+
+- Core stack management (deploy, start, stop, restart, update)
+- Dashboard, stacks page, deploy flow, logs
+- System info, memory validation
+- Git sync, app catalog, delete flow