feat(telemetry): add pre-quorum bootstrap sync diagnostics (WP-A1)

A freshly started node most often stalls before it ever peers or reaches
quorum, and that whole chain had no telemetry. Adds the six signals that
make it observable:

- dns_resolve_total / dns_resolve_latency_ms: configured-peer hostname
  resolution, emitted from OverlayImpl so libxrpl stays independent.
- overlay_connect_total / overlay_dial_latency_ms: outbound dial outcome
  by terminal reason, plus dial duration.
- handshake_negotiation_fail_total: protocol and network-id negotiation
  rejections, labelled by reason, so a misconfigured network is no longer
  indistinguishable from unreachable peers.
- unl_fetch_total and the unl_quorum gauge: validator-list fetch outcome
  per site and trusted key count against the required quorum. Without
  these a bad validators.txt leaves the node syncing forever with no
  signal.
- clock_close_offset_seconds: network close-time offset, which server_info
  hides below 60s but which stalls consensus participation.

Panels land in the Bootstrap row of the Ledger Sync Health dashboard, the
metrics are asserted by the workload validator, and both the reference and
the runbook flow describe them.

Levelization baseline regenerated: overlay now includes MetricMacros.h, so
the overlay/telemetry pair is reported one-way instead of bidirectional.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.github/scripts/levelization/results/loops.txt

@@ -17,5 +17,5 @@ Loop: xrpld.overlay xrpld.rpc
   xrpld.rpc ~= xrpld.overlay
 
 Loop: xrpld.overlay xrpld.telemetry
-  xrpld.telemetry ~= xrpld.overlay
+  xrpld.overlay > xrpld.telemetry