fix(security): validate WHIP/WHEP OPTIONS path params

[birme]

Summary

• Add a TypeBox params schema to the WHIP OPTIONS handler (/whip/:productionId/:lineId) validating productionId and lineId (String, minLength 1, maxLength 200).
• Add the same params schema to the WHEP OPTIONS handler (/whep/:productionId/:lineId).
• Existing response schemas are preserved; no other handlers touched.

Test plan

• npm run typecheck clean
• npm test all pass (243 tests; "worker process has failed to exit gracefully" warning is expected)

Closes #249