feat(telemetry): Phase 3 transaction tracing with protobuf context propagation

- TraceContext protobuf message for cross-node trace propagation
  (added to TMTransaction, TMProposeSet, TMValidation at field 1001)
- TraceContextPropagator.h: inline extractFromProtobuf/injectToProtobuf
- PeerImp::handleTransaction: tx.receive span with peer.id, peer.version,
  tx.hash, tx.suppressed, tx.status attributes
- NetworkOPsImp::processTransaction: tx.process span with tx.hash,
  tx.local, tx.path attributes
- Tempo search filters for tx.hash, tx.local, tx.status
- Unit tests for TraceContextPropagator (round-trip, edge cases)
- Levelization: xrpld.app/overlay > xrpld.telemetry dependencies

Translated from macro API (XRPL_TRACE_TX/SET_ATTR) to SpanGuard factory
pattern introduced in Phase 1c.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

@@ -237,6 +237,7 @@ xrpld.app > xrpl.basics
 xrpld.app > xrpl.core
 xrpld.app > xrpld.consensus
 xrpld.app > xrpld.core
+xrpld.app > xrpld.telemetry
 xrpld.app > xrpl.json
 xrpld.app > xrpl.ledger
 xrpld.app > xrpl.net
@@ -262,6 +263,7 @@ xrpld.overlay > xrpl.core
 xrpld.overlay > xrpld.consensus
 xrpld.overlay > xrpld.core
 xrpld.overlay > xrpld.peerfinder
+xrpld.overlay > xrpld.telemetry
 xrpld.overlay > xrpl.json
 xrpld.overlay > xrpl.ledger
 xrpld.overlay > xrpl.protocol