Add deterministic traverse-starter UI flow

[enricopiovesan]

Summary

• Adds `src/client/traverseOutput.ts` — `parseOutput()` validates and type-narrows the execution envelope into typed `TraverseStarterOutput` fields
• Updates `App.tsx` output panel to render `title`, `tags`, `noteType`, `suggestedNextAction`, `status` from runtime output — no local computation
• Falls back to raw JSON if the output shape doesn't match (forward-compatible)
• 6 new unit tests for `parseOutput`; 17 total

Closes #4

Definition of Done

• User can enter a short note
• UI sends input to Traverse runtime
• UI renders runtime-provided fields: title, tags, noteType, suggestedNextAction, status
• UI does not compute these fields locally
• Feature is deterministic — no live AI/model access required

Validation

npm run typecheck  # pass
npm run lint       # pass
npm run test       # 17 tests pass (4 files)