Add uint32_t dispatch_fail_count to the job_t wrapper struct (xce/types.h,
alongside submit_lsn, same in-memory-only/reset-on-failover precedent),
per Requirement 4.3. Data model only -- xce_job_t (wire type) untouched,
job.c untouched; increment/reset wiring and the bounded-retry threshold
check are tasks 3.1/3.3.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
