Tasks — mime-spec-conformance

Wire MimeEntrySchema.safeParse into registerMimeEntry; throw ParseError on failure.
Wire DetectInputSchema.safeParse into detect; throw ParseError on type-mismatched inputs (allow empty-input default per existing behaviour).
Add // schema: boundary-only annotations to wire-only result schemas.
Add **Verified by:** line under every MIME-NN requirement in openspec/specs/mime/spec.md.
Add src/db/db.spec-conformance.test.ts covering MIME-07 / MIME-12 / MIME-16 / MIME-20.
Confirm bun scripts/openspec-conformance.ts @suaveplan/mime reports zero errors.
Confirm bunx turbo lint typecheck test --filter=@suaveplan/mime is green.
Confirm bunx turbo test:coverage --filter=@suaveplan/mime reports 100/100/100/100.