Post-1.3: investigate slow session resume latency

## Summary
Manual testing during the 1.3 release pass showed session resume taking several seconds before the shell became usable.

## Observed
- Resuming an existing Capsem session felt noticeably slow.
- This was observed during manual end-user testing of the TUI / `capsem shell` path.

## Expected
- Resume should be fast enough to feel interactive, or the UI/TUI should expose precise progress so the delay is understandable.

## Notes
- Do not address in the 1.3 release lane unless it becomes release-blocking.
- Follow-up should measure resume stages with structured timing before optimizing.
- Check whether the delay is service route latency, profile readiness, disk/snapshot restore, shell attach, DB/status reads, or UI focus/render delay.

## Acceptance Criteria
- Add timing around resume phases.
- Record benchmark numbers before and after any change.
- UI/TUI reports progress if unavoidable latency remains.
- No new fallback path or alternate session state model.