Preserve 400 classification for malformed /api/upload bodies

[Copilot]

Summary

• /api/upload was regressing malformed upload requests into generic 500s when request.formData() threw before file-field validation. This change restores 400 client-error behavior for invalid upload bodies and preserves 5xx classification for real backend failures.
• Upload parse error handling
  • Wrap request.formData() failures as PublicApiError with status 400 (invalid_form_data).
  • Use default jsonError(error) in the route catch path so storage/database errors are not coerced to 400.
• Contract tests
  • Added coverage for:
    • non-form upload content type
    • malformed multipart upload body
  • Both assert 400 and no storage/database side effects.
  • Updated coupled upload cleanup tests to assert 500 for document/job insert failures.

constformData=awaitrequest.formData().catch((cause)=>{thrownewPublicApiError("Invalid upload form data.",400,{code: "invalid_form_data",causeName: causeinstanceofError ? cause.name : null,causeMessage: causeinstanceofError ? cause.message : null,});});// ...returnjsonError(error);

Verification

• npm run verify:cheap
• npm run verify:ui when UI, routing, styling, browser behavior, reduced-motion, or forced-colors behavior changed
• npm run verify:release before release or handoff confidence claims
• npm run format:check
• npm run check:production-readiness when clinical workflow, privacy, environment, Supabase, source governance, or deployment behavior changed
• npm run check:deployment-readiness when deployment startup, hosting, or rollout behavior changed

Clinical Governance Preflight

Complete this section when the change touches ingestion, answer generation, search/ranking, source rendering, document access, privacy, production env, or clinical output.

• Source-backed claims still require linked source verification before clinical use
• No patient-identifiable document workflow was introduced or expanded without explicit governance approval
• Supabase target remains Clinical KB Database (sjrfecxgysukkwxsowpy)
• Service-role keys and private document access remain server-only
• Demo/synthetic content remains clearly separated from real clinical sources
• Source metadata, review status, and outdated/unknown-source behavior remain conservative
• Deployment classification/TGA SaMD impact was checked when clinical decision-support behavior changed

Notes

• No schema, Supabase env, or deployment behavior changes.