Wire Live Metrics Into Process Strip

[csfh]

Parent

#179

What to build

Connect the metrics sampler to the selected Process detail strip so Cpu and Mem update live for the selected Direct Managed Process without changing Manifest row density.

Acceptance criteria

• Cpu and Mem in the strip update from the selected process metrics sampler.\n- [ ] Metrics reset when selected Managed Process changes.\n- [ ] Metrics for Off, errored without active PID, or unavailable processes render as —.\n- [ ] Metrics continue updating while Process Output is focused.\n- [ ] Metrics preserve stable field positions.\n- [ ] Strip remains responsive and does not sample more frequently than the configured cadence.\n- [ ] Tests cover selection changes, unavailable metrics, and live update propagation through the strip seam.

Blocked by

#186 and #187

[csfh]

Starting implementation.

[csfh]

PR ready: https://github.com/modoterra/stasium/pull/196\n\nVerification passed: bun run lint, bun run typecheck, bun run test, bun run format:check. CI checks passed.