Improve Clinical KB design and RAG hardening

[BigSimmo]

Summary

• upgrades the Clinical KB dashboard answer experience with compact scope controls, structured clinical sections, threshold tables, clearer Documents-mode states, and improved source viewer evidence handling
• includes the broader local RAG/search/indexing hardening already present on this branch
• preserves unrelated unstaged evidence-relevance edits in the local worktree; they are not included in this push

Verification

• npm test -- tests/ward-output.test.ts
• npm run typecheck
• npm run lint (0 errors; existing warnings remain in tests/private-access-routes.test.ts)
• npm run build
• targeted Playwright checks for demo answer flow, document search mode, and mobile document viewer evidence/PDF flow
• in-app browser QA on http://localhost:4298 with /api/local-project-id verified

Notes

• Draft PR because this branch is large and should be reviewed before merge.
• Original local codex/backup branch remains divergent from origin/codex/backup and was not force-pushed or merged.

[BigSimmo]

Superseded by #11, which contains the final local lint and evidence relevance fixes without force-pushing this divergent branch. Leaving this draft open for now rather than closing it automatically.

[BigSimmo]

Closed as superseded by merged PR #11. The final fixes landed on main in e042003 without preserving this stale divergent branch.