feat: Add Grafana dashboard and vector sync metric instrumentation

Implement comprehensive observability for vector database synchronization
with Grafana dashboard and Prometheus metrics.

## Part 1: Grafana Dashboard

Created all-in-one operations dashboard with 7 rows and 34 panels:

### Dashboard Structure:
- **Overview Row**: Request rate, error rate, P95 latency, active requests
- **HTTP Metrics (RED)**: Request/error rates by endpoint, latency percentiles
- **MCP Tools**: Call volume, error rates, execution duration by tool
- **Nextcloud API**: API calls/latency by app, retry patterns
- **OAuth & Authentication**: Token validations, exchanges, cache hit rate
- **Dependencies & Health**: Status for Nextcloud/Qdrant/Keycloak/Unstructured
- **Vector Sync**: Processing throughput, queue depth, Qdrant operations

### Helm Chart Integration:
- Added dashboard-configmap.yaml template for automatic provisioning
- Configured Grafana sidecar auto-discovery (label: grafana_dashboard="1")
- Added dashboards configuration section in values.yaml (opt-in)
- Updated Chart.yaml with dashboard annotations
- Enhanced NOTES.txt with dashboard deployment instructions
- Comprehensive documentation in dashboards/README.md

Dashboard supports dynamic filtering via variables:
- datasource: Prometheus data source selection
- namespace: Filter by Kubernetes namespace
- pod: Multi-select pod filtering
- interval: Query interval (1m/5m/10m/30m/1h)

## Part 2: Vector Sync Metric Instrumentation

Implemented metric recording throughout vector sync pipeline:

### metrics.py:
Added convenience functions:
- record_vector_sync_scan() - Track documents per scan
- record_vector_sync_processing() - Track processing duration/status
- record_qdrant_operation() - Track database operations
- update_vector_sync_queue_size() - Track queue depth

### scanner.py:
- Record number of documents found in each scan
- Enables monitoring of scan throughput

### processor.py:
- Record processing duration for each document
- Track success/failure status with timing
- Record Qdrant upsert/delete operations
- Handle all code paths (success, deletion, error)

### semantic.py:
- Wrap Qdrant query_points with try/except
- Record search operation success/failure

## Metrics Exposed:

- mcp_vector_sync_documents_scanned_total
- mcp_vector_sync_documents_processed_total{status}
- mcp_vector_sync_processing_duration_seconds (histogram)
- mcp_vector_sync_queue_size (gauge)
- mcp_qdrant_operations_total{operation,status}

This enables monitoring of:
- Scan and processing throughput
- Processing latency (P50/P95/P99)
- Error rates for processing and Qdrant operations
- Queue depth trends
- Complete observability of vector sync pipeline

## Testing:

Verified locally that metrics are recorded correctly:
- 36 documents scanned
- 3 documents processed (avg 7.5s each)
- 3 successful Qdrant upsert operations
- Search operations tracked

## Deployment:

Enable dashboard provisioning in Helm values:
```yaml
dashboards:
  enabled: true
  grafanaFolder: "Nextcloud MCP"
```

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

charts/nextcloud-mcp-server/templates/NOTES.txt

@@ -96,6 +96,30 @@ Your Nextcloud MCP Server has been deployed in {{ .Values.auth.mode }} authentic
    kubectl --namespace {{ .Release.Namespace }} exec -it deploy/{{ include "nextcloud-mcp-server.fullname" . }} -- curl -s http://localhost:{{ include "nextcloud-mcp-server.port" . }}/user/page | grep "Vector Sync"
 {{- end }}
 
+{{- if .Values.dashboards.enabled }}
+
+6. Grafana Dashboards:
+   - Dashboard provisioning: Enabled
+   - ConfigMap: {{ include "nextcloud-mcp-server.fullname" . }}-dashboard
+   - Grafana Folder: {{ .Values.dashboards.grafanaFolder }}
+
+   The dashboard will be automatically imported by Grafana if the sidecar is configured
+   to watch for ConfigMaps with label "grafana_dashboard: 1".
+
+   To manually import the dashboard:
+   kubectl --namespace {{ .Release.Namespace }} get configmap {{ include "nextcloud-mcp-server.fullname" . }}-dashboard -o jsonpath='{.data.nextcloud-mcp-server\.json}' | jq . > dashboard.json
+
+   Then import dashboard.json via Grafana UI (Dashboards → Import).
+{{- else }}
+
+6. Grafana Dashboards:
+   - Dashboard provisioning: Disabled
+   - To enable automatic dashboard provisioning, set: dashboards.enabled=true
+
+   Manual import option:
+   The dashboard JSON is available in the chart at charts/nextcloud-mcp-server/dashboards/nextcloud-mcp-server.json
+{{- end }}
+
 For more information and documentation:
 - GitHub: https://github.com/cbcoutinho/nextcloud-mcp-server
 - Documentation: https://github.com/cbcoutinho/nextcloud-mcp-server#readme

charts/nextcloud-mcp-server/templates/dashboard-configmap.yaml

@@ -0,0 +1,24 @@
+{{- if .Values.dashboards.enabled }}
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "nextcloud-mcp-server.fullname" . }}-dashboard
+  namespace: {{ .Release.Namespace }}
+  labels:
+    {{- include "nextcloud-mcp-server.labels" . | nindent 4 }}
+    {{- with .Values.dashboards.labels }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
+    # Grafana sidecar discovery labels
+    grafana_dashboard: "1"
+    {{- if .Values.dashboards.grafanaFolder }}
+    grafana_folder: {{ .Values.dashboards.grafanaFolder | quote }}
+    {{- end }}
+  annotations:
+    {{- with .Values.dashboards.annotations }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
+data:
+  nextcloud-mcp-server.json: |-
+{{ .Files.Get "dashboards/nextcloud-mcp-server.json" | indent 4 }}
+{{- end }}