Retranscribe from the Recents row menu

[maboa]

The ⋮ menu on a Recents row offers Star, Rename, Duplicate and Delete. Add Retranscribe: run the project's media through a transcription engine again, without the user having to find the file and go through the Transcribe dialog from scratch.

Why

A project already holds its media (kind: original in OPFS, or kind: link with a URL). Reasons to want a second pass over the same media are common: a different engine or model (Whisper vs Parakeet, a larger Whisper model), a different language, a fix in an engine (e.g. #671 once it lands), or simply a transcript that was hand-edited into a corner and is easier to redo than repair. Today that means re-uploading the file and starting over.

Behaviour

• Retranscribe opens the Transcribe dialog with the project's media already chosen (the OPFS file, or the link URL), so the user picks the engine, model and language as usual and presses Transcribe. Nothing runs without that step.
• The result replaces the transcript of this project — same media, same identity, same Recents row — rather than creating a new project. Anyone who wants to keep the old text can Duplicate first (the menu already has it), and the confirm should say so.
• Since the transcript is being replaced, ask before running: "Replace this project's transcript? The current text will be lost — Duplicate first to keep it."
• Provenance (Transcript provenance sidecars (TPME), off by default #668) records the new engine, model and parameters for the new transcript; the previous transcript's provenance is not carried over as a chain, it is replaced.
• Media kind: none (a transcript with no media) has nothing to retranscribe: the item is disabled with a hint, not hidden.
• A read-only project (open in another tab) can't be retranscribed: disabled with the read-only hint.

Out of scope

Batch retranscription (#528), and diffing the old transcript against the new.