feat(telemetry): wire A5-A7 and B1 signals through the pipeline

Registers the new gauges, renders them, asserts them and documents them, so
each signal reaches an operator rather than stopping at the emit site:

- MetricsRegistry: gauge registration for ledger_quorum_publish,
  nodestore_latency, peer_ledger_supply, peerfinder_slot_census and
  amendment_block, each guarded by the detached-callbacks check and
  tolerant of services that are not ready yet.
- Ledger Sync Health dashboard: panels for the new signals, filtered by
  the node template variable like every other board.
- Workload validation: the new series are asserted, so a signal that
  regresses to absent fails CI. Signals the local cluster structurally
  cannot produce, such as a replay fallback or an amendment block, are
  noted rather than asserted, which would fail red on a healthy run.
- Reference, runbook and glossary entries, including the diagnosis order
  for a node that has peers and validators but never validates.
- Regenerated levelization baseline: three new one-way edges from the
  telemetry and test modules, no new cycles.

Also drops an unused cstddef include from the macro tests, which the
include checker rejects.

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

.github/scripts/levelization/results/ordering.txt

@@ -200,6 +200,8 @@ tests.libxrpl > xrpl.basics
 tests.libxrpl > xrpl.config
 tests.libxrpl > xrpl.core
 tests.libxrpl > xrpld.app
+tests.libxrpl > xrpld.overlay
+tests.libxrpl > xrpld.peerfinder
 tests.libxrpl > xrpld.telemetry
 tests.libxrpl > xrpl.json
 tests.libxrpl > xrpl.ledger
@@ -336,6 +338,7 @@ xrpld.telemetry > xrpl.core
 xrpld.telemetry > xrpld.consensus
 xrpld.telemetry > xrpld.core
 xrpld.telemetry > xrpl.json
+xrpld.telemetry > xrpl.ledger
 xrpld.telemetry > xrpl.nodestore
 xrpld.telemetry > xrpl.protocol
 xrpld.telemetry > xrpl.rdb