Phase 5b: Add ledger/peer/tx spans + expand Grafana dashboards

[pratikmankawde]

PR Chain: #6436 → #6437 → #6438 → #6424 → #6425 → #6426 → #6427 → #6433 (this PR) / #6439
Base: pratik/otel-phase5-docs-deployment

High Level Overview of Change

Add 6 new OpenTelemetry spans to instrument ledger building, ledger validation,
ledger storage, transaction application, and peer proposal/validation message
receipt. Expand all Grafana dashboards from 4 to 8 panels each and add 2 new
dashboards (Ledger Operations, Peer Network), bringing the total to 32 panels
across 5 dashboards. Each panel now includes a description explaining what it
shows and how the PromQL query calculates the metric.

Context of Change

Phase 5a (the base branch pratik/otel-phase5-docs-deployment) delivered
consensus spans, the observability stack (otel-collector, Jaeger, Prometheus,
Grafana), and integration tests. During review, we identified that the
trace_ledger config category existed with its XRPL_TRACE_LEDGER macro but
had zero spans using it, and trace_peer had only 1 span (tx.receive).
Dashboard panels were limited to 4 per dashboard with no panel descriptions.

This PR fills those gaps:

New spans (6, bringing total from 10 to 16):

Span	File	Category	Key Attributes
ledger.build	BuildLedger.cpp:31	trace_ledger	xrpl.ledger.seq
ledger.validate	LedgerMaster.cpp:915	trace_ledger	xrpl.ledger.seq, xrpl.ledger.validations
ledger.store	LedgerMaster.cpp:409	trace_ledger	xrpl.ledger.seq
tx.apply	BuildLedger.cpp:88	trace_transactions	xrpl.ledger.tx_count, xrpl.ledger.tx_failed
peer.proposal.receive	PeerImp.cpp:1667	trace_peer	xrpl.peer.id, xrpl.peer.proposal.trusted
peer.validation.receive	PeerImp.cpp:2264	trace_peer	xrpl.peer.id, xrpl.peer.validation.trusted

Dashboard changes (12 → 32 panels):

• RPC Performance: 4 → 8 panels (+ throughput, success/error, top commands, WebSocket)
• Transaction Overview: 4 → 8 panels (+ heatmap, tx.apply duration, peer receive, failed rate)
• Consensus Health: 4 → 8 panels (+ mode tracking, accept vs close, validation vs close, heatmap)
• Ledger Operations: NEW, 8 panels (build/validate/store rates and durations)
• Peer Network: NEW, 4 panels (proposal/validation receive, trusted vs untrusted)

Type of Change

• New feature (non-breaking change which adds functionality)
• Tests (you added tests for code that already exists, or your new feature included in this PR)
• Documentation update

API Impact

None. This change only adds internal observability instrumentation (OpenTelemetry
spans) and Docker-based Grafana dashboards. No public API, libxrpl, or peer
protocol changes.

Test Plan

Integration test (bash docker/telemetry/integration-test.sh) passes 24/24
with all 16 span types verified across a 6-node consensus network:

• Phase 2 (RPC): rpc.request, rpc.process, rpc.command.* — 5 traces each
• Phase 3 (TX): tx.process, tx.receive, tx.apply — 5 traces each
• Phase 4 (Consensus): consensus.proposal.send, consensus.ledger_close, consensus.accept, consensus.validation.send — 5 traces each
• Phase 5 (Ledger): ledger.build, ledger.validate, ledger.store — 5 traces each
• Phase 5 (Peer): peer.proposal.receive, peer.validation.receive — 5 traces each
• Spanmetrics: 22 Prometheus series with duration histograms
• Grafana: healthy with 5 dashboards, 32 panels

[codecov]

Codecov Report

❌ Patch coverage is 43.75000% with 9 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (pratik/otel-phase5-docs-deployment@85f583f). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/xrpld/overlay/detail/PeerImp.cpp	0.0%	6 Missing ⚠️
src/xrpld/app/ledger/detail/LedgerMaster.cpp	40.0%	3 Missing ⚠️

Additional details and impacted files

@@                         Coverage Diff                          @@
##             pratik/otel-phase5-docs-deployment   #6433   +/-   ##
====================================================================
  Coverage                                      ?   79.7%           
====================================================================
  Files                                         ?     851           
  Lines                                         ?   67968           
  Branches                                      ?    7607           
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  Hits                                          ?   54182           
  Misses                                        ?   13786           
  Partials                                      ?       0           

Files with missing lines	Coverage Δ
src/xrpld/app/ledger/detail/BuildLedger.cpp	92.9% <100.0%> (ø)
src/xrpld/app/ledger/detail/LedgerMaster.cpp	42.7% <40.0%> (ø)
src/xrpld/overlay/detail/PeerImp.cpp	5.8% <0.0%> (ø)

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