Properly fix MIDI loop timing at end of record, including overdubs

[malisimat]

No description provided.

[Copilot]

Pull request overview

This PR adjusts how MIDI loop playback/overdub timing is anchored when transitioning out of record/overdub, aiming to make end-of-record MIDI timing consistent (including overdubs) by basing MIDI phase on trigger/quantisation timing rather than audio play position.

Changes:

• Pass MIDI quantisation error into LoopTake::Play() and use it to set the initial MIDI visual/play index.
• Rework MIDI overdub merge to rebase source MIDI events relative to the captured source start sample (and stop shifting punch windows/events by a phase offset).
• Update existing MIDI timing assertions and add a regression test covering double-length overdubs with non-zero audio play positions.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
test/JammaLib_Tests/src/midi/MidiLoop_Tests.cpp	Updates expectations for overdub/playback timing and adds a regression test for “no punch, double-length” overdub timing.
JammaLib/src/engine/Station.cpp	Threads quantisation error (errorSamps) into LoopTake::Play() at record/overdub end triggers.
JammaLib/src/engine/LoopTake.h	Extends LoopTake::Play() signature with optional midiQuantisationErrorSamps; updates helper signature to remove phase-offset argument.
JammaLib/src/engine/LoopTake.cpp	Implements new MIDI start index logic and rebased-source overdub merge behavior (including additional verbose diagnostics).