[Transcribe] Graceful interruption support

[yqzhishen]

Behavior before this PR

• Even if the user closes the progress dialog manually, the MIDI and pitch extraction tasks continue and generate a voice part.
• If any task raises an error, the modal dialog doesn't close.

Bahavior after this PR

• Once the progress dialog is closed, the running inference session terminates gracefully, the task returns null, the memory is released, and nothing will be generated.
• UI cleanup happens in both sucess and failure paths.

[Copilot]

Pull request overview

Adds cooperative cancellation for the Transcribe workflow so that closing the progress dialog attempts to terminate ONNX inference and prevents generating a new voice part.

Changes:

• Hook progress dialog close to trigger interruption of SOME/GAME/RMVPE inference and skip part creation.
• Add RunOptions-based termination + Interrupt() implementations to SOME/GAME/RMVPE transcribers.
• Update MidiExtractor.Transcribe() to treat OperationCanceledException as a graceful cancel (return null) and expose a base Interrupt() hook.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
OpenUtau/Views/MainWindow.axaml.cs	Wires dialog-close cancellation into transcribe + pitch inference pipeline and guards part creation.
OpenUtau.Core/Analysis/MidiExtractor.cs	Catches cancellation and adds virtual Interrupt() for derived extractors.
OpenUtau.Core/Analysis/Some.cs	Uses RunOptions termination + maps ORT termination to OperationCanceledException.
OpenUtau.Core/Analysis/Game.cs	Adds RunOptions termination across pipeline sessions + Interrupt().
OpenUtau.Core/Analysis/Rmvpe.cs	Adds RunOptions termination + Interrupt() and makes Infer return nullable on termination.

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