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/ledger/app.py

@@ -2,6 +2,7 @@ from fastapi import FastAPI, Request
 from fastapi.responses import JSONResponse
 from pydantic import BaseModel, field_validator
 from opentelemetry import trace
+from opentelemetry.trace import StatusCode
 from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
 from opentelemetry.instrumentation.sqlalchemy import SQLAlchemyInstrumentor
 
@@ -75,6 +76,9 @@ async def readyz():
         async with normal_engine.connect() as conn:
             await conn.exec_driver_sql("SELECT 1")
     except Exception as exc:
+        span = trace.get_current_span()
+        span.record_exception(exc)
+        span.set_status(StatusCode.ERROR, str(exc))
         logger.exception(f"readyz check failed: {exc}")
         return JSONResponse(status_code=503, content={"status": "unavailable"})
     return {"status": "ok"}