fix(ci): repair invalid LLM JSON escapes in issue translation

[Wibias]

Summary

• Long Korean issue translation in run 30208536337 produced a complete English title/body, but JSON.parse failed on invalid \' escapes (Kiro\'s).
• Parse step fail-closed with requires_translation=false, so Apply inline translation was skipped.
• Repair invalid JS-style escapes inside JSON strings before parse; regression test mirrors that payload.

Test plan

• node --test .github/scripts/parse-issue-translation-response.test.cjs
• Replayed the failing job model response through the new parser → requires_translation: true
• After merge, re-run Translate on the Korean Kiro 429 issue (workflow_dispatch) and confirm title/body update

[Wibias]

Opened against the fork by mistake; recreating against lidge-jun/opencodex.