fix(telemetry): review fixes — flush/shutdown ordering, session retirement, whole-exporter passthrough

Three review findings, each pinned by a red test first:

- The OTel backend retains the latest turn-boundary flush promise and
  shutdown() awaits it before provider.shutdown(): the SDK's
  concurrent-flush guard makes the shutdown-internal flush return early
  while one is in flight, silently dropping everything enqueued after
  the flush snapshot (including the coordinator's dispose-time shutdown
  markers).
- The coordinator retires sessions from the adopted set on
  session/disposed (mirroring the persistence coordinator): a long-lived
  backend no longer retains closed sessions and their event logs, and
  final unload no longer stamps shutdown markers for dead sessions.
- The exporter config passes through whole to OTLPLogExporter and its
  type/JSDoc now advertise the full OTLPExporterNodeConfigBase shape:
  rebuilding url/headers only silently dropped documented SDK options
  (timeoutMillis, compression, keepAlive, ...).

docs/cordis-catalog/services.md

@@ -1554,7 +1554,7 @@ flush?(): void
 abstract shutdown(): Promise<void>
 ```
 
-Source: [`packages/telemetry/session-telemetry/src/index.ts:125`](../../packages/telemetry/session-telemetry/src/index.ts)
+Source: [`packages/telemetry/session-telemetry/src/index.ts:129`](../../packages/telemetry/session-telemetry/src/index.ts)
 
 ## `ctx.tokenMeter` — `TokenMeterService`