port(omniroute): add opt-in OpenTelemetry routing traces #1128

Outcome

DurinDoor has local request correlation and proxy timeline but no OTEL exporter. Compare OmniRoute tracing integration and preserve redaction.

Evidence and source state

DurinDoor baseline: 93f6de64c69b17d52f790d6f14d09a74cffc7fa5.

• src/sse/utils/requestCorrelation.js
  OmniRoute source snapshot: 61e07fb7e0d4e1e76111495d3718c9e4d06d2a62 on release/v3.8.52.
• open-sse/services/routing/otel.ts

Implementation subtasks and acceptance criteria

• Trace admission, routing attempts, provider TTFT and terminal outcome with stable IDs.
• Exclude raw prompts, credentials and high-cardinality user values by default.
• Exporter failures must not fail inference; bound queue and shut down cleanly.

Dependencies

No hard predecessor. Complete source review and reproduction/discovery before implementation.

Parent epic: #1063. Roadmap: #1056. Priority P2. Stage 3.

Delivery contract

Planning ticket only. No implementation, runtime test, live-provider call, deployment or stored-data mutation was performed in this audit. Before a port, confirm a merged final upstream diff or a reachable source commit, compare local equivalents/tests, and preserve local auth/routing/quota/database contracts. Open upstream work remains a review candidate. Use port(omniroute): title and target a focused PR at bloodf/durindoor:main. Behavior changes require a focused test plus docs. Run npm run lint and cd tests && npm run test:ci; never add baseline failures. Pure docs/CI edits may skip runtime tests. Regenerate registry/agent indexes with their scripts. Preserve stored credentials and unrelated work.