Fix Grafana dashboards mount; keep connector OTLP (AWG_CONF must omit DNS=)

- deploy/docker-compose.yml: mount the provisioned dashboards at
  /etc/grafana/dashboards, not /var/lib/grafana/dashboards — the grafana-data
  volume mounts over the latter and shadows the nested bind, so the provider
  logged "readdirent /var/lib/grafana/dashboards: no such file or directory".
  dashboards.yaml provider path updated to match.
- Connector telemetry stays OTLP. The VPN sidecar's netns reaches the collector's
  internal IP fine (connected route, off-tunnel), but the sidecar's DNS hijacks
  name resolution: AWG_CONF must NOT carry a DNS= directive, else otelcol won't
  resolve ("produced zero addresses"). Without DNS= the netns uses Docker's
  resolver (resolves both otelcol and api.telegram.org). Documented in
  deploy/README.md (AWG_CONF row + wiring note), ARCHITECTURE §13, compose comment.

deploy/docker-compose.yml

@@ -125,6 +125,12 @@ services:
       TELEGRAM_API_BASE_URL: ${TELEGRAM_API_BASE_URL:-}
       TELEGRAM_LOG_LEVEL: ${LOG_LEVEL:-info}
       TELEGRAM_SERVICE_NAME: scrabble-telegram
+      # The connector shares the VPN sidecar's netns. Routing to the collector's
+      # internal IP stays off the tunnel (connected route), but the sidecar's DNS
+      # hijacks name resolution: AWG_CONF must NOT carry a `DNS=` directive, else
+      # `otelcol` won't resolve ("produced zero addresses"). Without DNS= the netns
+      # uses Docker's resolver, which resolves both otelcol and api.telegram.org
+      # (see deploy/README.md).
       TELEGRAM_OTEL_TRACES_EXPORTER: otlp
       TELEGRAM_OTEL_METRICS_EXPORTER: otlp
       OTEL_EXPORTER_OTLP_ENDPOINT: http://otelcol:4317
@@ -199,7 +205,10 @@ services:
       GF_SECURITY_ADMIN_PASSWORD: ${GRAFANA_ADMIN_PASSWORD:-admin}
     volumes:
       - ./grafana/provisioning:/etc/grafana/provisioning:ro
-      - ./grafana/dashboards:/var/lib/grafana/dashboards:ro
+      # Dashboards live under /etc/grafana (NOT /var/lib/grafana, which the
+      # grafana-data volume mounts over — a nested bind there is shadowed and the
+      # provider logs "no such file or directory").
+      - ./grafana/dashboards:/etc/grafana/dashboards:ro
       - grafana-data:/var/lib/grafana
     networks: [internal]