v0.44.0: less waiting, and more caught before the render

proofcut is an AI video editor that proves its cuts. It is an MCP server
over ffmpeg, whisper, MLT and OpenTimelineIO. An agent, the proofcut
command line, or the browser window takes your recordings and returns a
finished, mastered film: cut by transcript, with b-roll hung off the words,
cards, captions, and a score under the voice. It renders on your own machine,
then transcribes the render and checks that it says what the edit says.
It is source-available under PolyForm Shield 1.0.0: any use is allowed except
building a product that competes with it.

Since v0.43.0: less waiting, and more caught before the render.

• The models remember what they already said. Whisper, the vision model
  and the face detector keep their answers in one store outside every
  project, keyed by the media's content and what the model was asked. A
  second project on the same shoot, or a fresh start on the same footage,
  pays no model time. proofcut doctor shows the store, and
  proofcut setup --clear empties it.
• Render on an unchanged edit, and the file comes back at once. When
  nothing has moved since the last render, the window hands back that file
  and runs only the checks.
• A retake the cut kept is named before you render. transcript_checks
  now reads the words the timeline will play and points at any line said
  twice back to back, with both takes' word ranges ready to cut. It lists
  candidates, not verdicts: a script that repeats a line on purpose reads
  the same.
• Animated graphics that run on their own clock just work. A page that
  animates from requestAnimationFrame, performance.now or Date now
  draws the right frame at every instant, without the seek hook it used to
  need. A page that draws nothing at all, usually a script that failed, is
  refused at capture instead of going over the film as a blank.
• Every render says what made it. The render log records a fingerprint
  of the file and the proofcut, melt and ffmpeg versions that wrote it,
  beside the edit it was made from.
• Bookmarks on the ruler. Drop one at the playhead and jump back to it.
  A bookmark sits on the recording, so cutting around it never moves it.
• A melt that crashes is run again. On the Macs, melt now and then died
  mid-render and a plain re-run passed. proofcut retries it twice and says
  so, and a render that still fails reports melt's own error.
• A logo.

Where it runs. Nothing changed since v0.43.0: Linux is where proofcut was
built and measured. An Intel Mac, a Windows laptop and GitHub's Windows and
Apple silicon runners each take the demo to a checked render. No person has
run it on Apple silicon by hand yet, and that is still the report worth
having (issue #1).

Start with docs/DEMO.md.
It takes two minutes and runs on media the repo generates itself. If
proofcut doctor shows a ✗ on your machine, that output is the most useful
thing you can send.