feat(monitoring): complete monitoring pipeline and fix presentation flag persistence

add superadmin monitoring dashboard with protected route, menu entry, and monitoring data client
add monitoring overview API endpoint and improve log serialization/aggregation for dashboard use
extend listener health/log handling with robust status/event/timestamp normalization and screenshot payload extraction
improve screenshot persistence and retrieval (timestamp-aware uploads, latest screenshot endpoint fallback)
fix page_progress and auto_progress persistence/serialization across create, update, and detached occurrence flows
align technical and project docs to reflect implemented monitoring and no-version-bump backend changes
add documentation sync log entry and include minor compose env indentation cleanup

README.md

@@ -225,6 +225,8 @@ For detailed deployment instructions, see:
   
 ## Recent changes since last commit
 
+- Monitoring system: End-to-end monitoring is now implemented. The listener ingests `logs/*` and `health` MQTT topics, the API exposes monitoring endpoints (`/api/client-logs/monitoring-overview`, `/api/client-logs/recent-errors`, `/api/client-logs/<uuid>/logs`), and the superadmin dashboard page shows live client status, screenshots, and recent errors.
+- Presentation persistence fix: Fixed persistence of presentation flags so `page_progress` and `auto_progress` are reliably stored and returned for create/update flows and detached occurrences.
 - Video / Streaming support: Added end-to-end support for video events. The API and dashboard now allow creating `video` events referencing uploaded media. The server exposes a range-capable streaming endpoint at `/api/eventmedia/stream/<media_id>/<filename>` so clients can seek during playback.
 - Scheduler metadata: Scheduler now performs a best-effort HEAD probe for video stream URLs and includes basic metadata in the retained MQTT payload: `mime_type`, `size` (bytes) and `accept_ranges` (bool). Placeholders for richer metadata (`duration`, `resolution`, `bitrate`, `qualities`, `thumbnails`, `checksum`) are emitted as null/empty until a background worker fills them.
 - Dashboard & uploads: The dashboard's FileManager upload limits were increased (to support Full-HD uploads) and client-side validation enforces a maximum video length (10 minutes). The event modal exposes playback flags (`autoplay`, `loop`, `volume`, `muted`) and initializes them from system defaults for new events.
@@ -235,7 +237,6 @@ For detailed deployment instructions, see:
 These changes are designed to be safe if metadata extraction or probes fail — clients should still attempt playback using the provided `url` and fall back to requesting/resolving richer metadata when available.
 
 See `MQTT_EVENT_PAYLOAD_GUIDE.md` for details.
-  - `infoscreen/{uuid}/group_id` - Client group assignment
 
 ## 🧩 Developer Environment Notes (Dev Container)
 - Extensions: UI-only `Dev Containers` runs on the host UI; not installed inside the container to avoid reinstallation loops. See `/.devcontainer/devcontainer.json` (`remote.extensionKind`).
@@ -381,6 +382,9 @@ mosquitto_sub -h localhost -t "infoscreen/+/heartbeat" -v
 ### Health & Monitoring
 - `GET /health` - Service health check
 - `GET /api/screenshots/{uuid}.jpg` - Client screenshots
+- `GET /api/client-logs/monitoring-overview` - Aggregated monitoring overview for dashboard (superadmin)
+- `GET /api/client-logs/recent-errors` - Recent error feed across clients (admin+)
+- `GET /api/client-logs/{uuid}/logs` - Filtered per-client logs (admin+)
 
 ## 🎨 Frontend Features
 
@@ -444,6 +448,10 @@ mosquitto_sub -h localhost -t "infoscreen/+/heartbeat" -v
    - Real-time event status: shows currently running events with type, title, and time window
    - Filters out unassigned groups for focused view
    - Resource-based Syncfusion timeline scheduler with resize and drag-drop support
+- **Monitoring**: Superadmin-only monitoring dashboard
+   - Live client health states (`healthy`, `warning`, `critical`, `offline`) from heartbeat/process/log data
+   - Latest screenshot preview and process metadata per client
+   - System-wide recent error stream and per-client log drill-down
  - **Program info**: Version, build info, tech stack and paginated changelog (reads `dashboard/public/program-info.json`)
 
 ## 🔒 Security & Authentication
@@ -474,7 +482,7 @@ mosquitto_sub -h localhost -t "infoscreen/+/heartbeat" -v
 - MQTT: Pub/sub functionality test
 - Dashboard: Nginx availability
 - **Scheduler**: Logging is concise; conversion lookups are cached and logged only once per media.
-- Dashboard: Nginx availability
+- Monitoring API: `/api/client-logs/monitoring-overview` and `/api/client-logs/recent-errors` for live diagnostics
 
 ### Logging Strategy
 - **Development**: Docker Compose logs with service prefixes