New-session persistence is lazy: after `/new`, the JSONL is not created
until assistant output exists. Exiting before any assistant message left
the per-terminal breadcrumb pointing at a not-yet-materialized file, which
`readTerminalBreadcrumbEntry` rejected (missing target), so `continueRecent`
fell back to `findMostRecentSession` and resurrected the pre-`/new` transcript.
`/new` now records a durable `fresh` breadcrumb boundary. The reader returns a
fresh breadcrumb even when its target is absent (with `exists:false`), and
`continueRecent` honors it by starting fresh instead of falling back. The crumb
is re-stamped non-fresh once the session materializes, so a genuinely
stale/deleted breadcrumb still falls back to the most-recent session. The
breadcrumb write is now synchronous so the fresh->materialized re-stamp cannot
reorder.
Fixes#5730
- Added session-domain modules and exports for session-entries, context, listing, loader, and migrations.
- Changed persistence to async append writes plus writeTextAtomic, removing sync line APIs.
- Added compaction-aware session context rebuild with dangling tool-call cleanup.
- Added resumable session resolution with status inference, id/stem/suffix matching, and backup recovery.
roboomp