fix(ui-tui): redraw after session resume

[LeonSGP43]

Summary

• force a full Ink redraw on the immediate resume snap after switching TUI sessions
• keep the resume scroll helper isolated in a small module with focused coverage
• preserve the existing sticky follow-up snaps while fixing the stale first paint

Testing

• ./node_modules/.bin/vitest run src/app/sessionResumeView.test.ts
• ./node_modules/.bin/eslint src/app/useSessionLifecycle.ts src/app/sessionResumeView.ts src/app/sessionResumeView.test.ts
• ./node_modules/.bin/esbuild src/app/sessionResumeView.ts --bundle --platform=node --format=esm --external:@hermes/ink --external:react >/dev/null
• ./node_modules/.bin/esbuild src/app/sessionResumeView.test.ts --bundle --platform=node --format=esm --external:vitest --external:@hermes/ink >/dev/null
• git diff --check

Closes #62170

[teknium1]

Thanks for isolating the stale first-paint path and reusing the existing Ink redraw primitive.

Problems

• The Closes #62170 linkage is broader than this implementation. The helper is scheduled only after activation/resume (ui-tui/src/app/useSessionLifecycle.ts:322, :376), while #62170 separately reports normal live assistant responses staying invisible and says /redraw does not fix that symptom. This change cannot run for those later stream updates.

Suggested changes

• Keep this focused stale-resume repaint fix, but remove Closes #62170 or split the unresolved live-update symptom into a follow-up.

Automated hermes-sweeper review.

[teknium1]

This repaint is intentionally limited to the first resume snap. Since #62170 also reports a live-stream freeze after the resume completes, please avoid closing that entire issue with this PR unless that remaining symptom is split into a follow-up.

[teknium1]

Merged via PR #86332 as part of the stale-repaint class fix (TUI focus regain / session resume / dashboard PTY reattach). Your commit was cherry-picked onto current main with your authorship preserved in git log. Thank you!