fix: stabilize LumaCare streaming UX

[kuanzema]

Summary

• Keep the LumaCare guide viewport stable across waiting, live streaming, completion, tablet, and phone layouts.
• Improve waiting, live-streaming, stop, history, and responsive states without exposing implementation details in family-facing guides.
• Isolate every stream by caregiver and client run ID so stop/retry and account switching cannot mix responses.
• Preserve checked versus pending care tasks, and make explicit cancellation safe even before the upstream session ID arrives.
• Let ordinary transport disconnects finish in the background so guides remain recoverable from history.

Test Coverage

• Added guide-formatting coverage for implementation-detail filtering and checklist state.
• Added responsive layout-contract coverage for desktop, tablet, and phone guide heights.
• Existing SSE parsing and cross-user ownership tests remain green.
• Tests: 17/17 pass across both workspaces.

Pre-Landing Review

• Manual checklist review: no open findings.
• Adversarial review: found and fixed per-run cancellation, caregiver-switch isolation, retry races, checklist-state loss, duplicate cancellation, and transport-disconnect recovery issues.
• Final adversarial re-review: clean.

Design Review

• Responsive guide layout verified at desktop, tablet, and phone breakpoints.
• Live browser measurement: guide body remains 320px from waiting through completion at the tested compact viewport.

Eval Results

No prompt-related files changed; evals were not applicable.

Scope Drift

Scope Check: CLEAN. Changes are limited to LumaCare waiting/streaming UX, responsive layout, cancellation safety, tests, and matching documentation.

Plan Completion

No plan file was used for this focused bug fix.

Verification Results

• npm test: 17/17 tests pass.
• npm run build: both Vite builds and server TypeScript checks pass.
• npm audit --omit=dev --audit-level=high: 0 vulnerabilities.
• Live checks: 25ms stop, immediate retry, caregiver switch during streaming, full completion, and stable 320px guide viewport all pass.

Documentation

• demos/02-lumacare/README.md: documents the stable guide viewport, isolated streaming, explicit per-run cancellation, and expanded test coverage.

Test plan

• Run all workspace tests
• Build and type-check both workspaces
• Verify waiting → streaming → completion height stability
• Verify immediate stop → retry
• Verify caregiver switching does not leak or mix streamed content