feat: make the Cursor coding app the primary Harvard demo

[kuanzema]

Summary

• Makes the Cursor-style coding app the primary Build a Cursor in 3 Steps workshop demo.
• Moves LumaCare into a separate secondary reference workspace.
• Adds independent setup guides, environment templates, agent mappings, servers, frontends, and tests for both demos.
• Adds root npm workspace commands so contributors can run, test, and build both applications consistently.
• Updates repository copy, contribution guidance, and ignored runtime-data paths for the new structure.

Test Coverage

• 12 unit tests passed across both workspaces.
• SSE parsing covers split chunks, malformed frames, JSON event dispatch, and unknown event types.
• Ownership tests cover creator access, cross-user isolation, and status updates.
• Interactive UI behavior was build- and smoke-verified; no browser E2E framework is configured.

Pre-Landing Review

• Corrected two copied LumaCare identifiers in the primary coding workspace.
• No credential, unsafe HTML, shell, SQL, or dependency-audit findings.

Design Review

• Added explicit keyboard focus indicators to the Cursor-style interface.
• Responsive desktop and narrow-screen layouts are included.

Eval Results

No prompt-related files changed; evals were skipped.

Plan Completion

No plan file was used for this change.

Verification Results

• npm test — 12 passed, 0 failed
• npm run build — both Vite builds and server typechecks passed
• npm audit --omit=dev --audit-level=high — 0 vulnerabilities
• Both development servers returned healthy responses with the correct product title

Test plan

• Cursor coding workspace tests
• LumaCare workspace tests
• Production builds for both workspaces