Phase 9E.1: extract transcription controller

[FernandoAbishai]

Summary

• extract transcription job/run lifecycle from App into a vertical useTranscriptionController hook
• preserve stale-run, retry, cancel, progress, and post-transcription routing behavior
• update transcription smokes to follow and enforce the new ownership boundary

Scope

• no backend or project schema changes
• no editor/AI store rewrite
• no AI, full-video export, or clip export changes
• no generic job manager

Validation

• all 22 frontend test:* scripts
• npm run smoke:golden-creator-path
• npm run lint
• npm run build:frontend
• git diff --check
• two independent blocker/high reviews: green

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