TypeScript job handles now expose structured progress through
`progress()` and an optional synchronous callback to `wait()`. Snapshots
preserve unknown fields and missing counters, and job listings include
progress and pause state. Existing `status()` strings and no-argument
`wait()` behavior remain compatible.
Wait callbacks observe the existing backend poller. Observer exceptions
are logged without changing the job outcome. A best-effort ETA is
available only from compatible samples with positive progress, and is
omitted during initialization, queueing, or pause.
Part of ENT-3500.
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Co-authored-by: EC2 Default User <ec2-user@ip-172-31-12-104.us-east-2.compute.internal>