Record swallowed exceptions on their spans

Where an error is caught and logged under a span that would otherwise
stay clean, also record_exception and set ERROR on that span: the
CONSUMER span when a stream message fails, fraud.score_transaction when
the sanctions call times out or fails, and the SERVER span of every
/readyz check (a 503 already made it ERROR, but without the exception).

Left alone where instrumentation already records it: ledger's app-wide
exception handler (FastAPI SERVER span), caught httpx errors (CLIENT
span), and the stream publish failure (PRODUCER span). The consumers'
failed reads run outside any span, so they stay log-only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/audit/consumer.py

@@ -5,7 +5,7 @@ import logging
 import sqlalchemy as sa
 from opentelemetry import propagate, trace
 from opentelemetry.instrumentation.utils import suppress_instrumentation
-from opentelemetry.trace import SpanKind
+from opentelemetry.trace import SpanKind, StatusCode
 
 from common.db import Session
 from common.redis_client import redis_client
@@ -82,9 +82,11 @@ async def run():
                         "messaging.consumer.group.name": GROUP,
                         "messaging.message.id": msg_id,
                     },
-                ):
+                ) as span:
                     try:
                         await _handle(fields)
-                    except Exception:
+                    except Exception as exc:
+                        span.record_exception(exc)
+                        span.set_status(StatusCode.ERROR, str(exc))
                         logger.exception(f"audit failed to process message {msg_id}")
                     await redis_client.xack(settings.stream_name, GROUP, msg_id)