Parse the UTC creation timestamp embedded in a session/thread id (YYYYMMDD-HHMMSS-<hex8> or the kit-minted t-YYYYMMDD-HHMMSS-<hex8>). Returns null for the legacy date-only format (YYYYMMDD-<hex12>) — callers should treat those as "old".
YYYYMMDD-HHMMSS-<hex8>
t-YYYYMMDD-HHMMSS-<hex8>
YYYYMMDD-<hex12>
Parse the UTC creation timestamp embedded in a session/thread id (
YYYYMMDD-HHMMSS-<hex8>or the kit-mintedt-YYYYMMDD-HHMMSS-<hex8>). Returns null for the legacy date-only format (YYYYMMDD-<hex12>) — callers should treat those as "old".