stream_id_compare's lex-fallback branch was a footgun: a malformed id
that sorts lex-greater than a real one would pin live-tail dedup
forever, dropping every subsequent legitimate event silently. Both
current callers in application/api/events/routes.py pre-validate
inputs against _STREAM_ID_RE before calling, so changing the function
to raise ValueError is a no-op on the happy path and turns the future-
caller footgun into a loud failure.
746bcbc5f9