Add opt-in local transcription with managed installation, cache warm-up,
and a one-time backend choice while preserving native-caption priority.
Correct frame timing and coverage, caption provenance and download
ownership, configuration parsing, provider pairing, and partial reports.
Update cross-host instructions, packaging, and test-gated release CI.
Validate 198 isolated tests, real local English and Spanish inference,
network-denied warm-cache inference, live captions/media, and packaging.
Record platform and account-dependent acceptance limits separately.
