Freeze: Fixed group-frozen tracks going silent when not rendered to any output device

[drowaudio]

Summary

Group-frozen tracks could go silent with no error. Two fixes:

1. TrackOutput::outputsToDevice now matches a track whose output is stored as a device ID. It resolves the ID and compares the device's name.
2. Edit::updateFrozenTracks now unfreezes any group-frozen track that didn't make it into a device's freeze render (e.g. it's muted, or its output device isn't available), and shows a warning, instead of leaving it frozen and silent.

Root cause

• Group freeze renders one file per WaveOutputDevice. A track is only included if getOutput().outputsToDevice (outputDevice->getName(), true) is true and it isn't muted.
• Since 9ed2e5d5526 ("Refactored TrackOutput to use device IDs rather than names", 2024-08), TrackOutput::outputDevice holds a device ID. outputsToDevice was still comparing it with a device name, so a track routed to a specific device never matched. Only the "(default audio output)" alias path still worked.
• When no track qualifies, updateFrozenTracks skips the render silently. The tracks keep frozen = true, so createNodeForTrack drops them from the live graph, and createNodeForFrozenOutputDevice has no file to play. The result is a frozen, silent track and no error.

Regression tests (tracktion_Renderer.test.cpp, freeze block)

• "Track Freeze: Group freeze matches a track to its output device" uses the hosted EnginePlayer device, so it's deterministic without audio hardware. It checks the default alias and a specific device ID. The specific-ID case failed before the fix.
• "Track Freeze: Group freezing a track that can't be rendered unfreezes it": a muted track, and a track whose output device doesn't exist, both end up unfrozen with no freeze files. Both failed before the fix (the track stayed group-frozen).
• "Track Freeze: Frozen wave clip/synth track is audible in the playback graph": individual freeze playback coverage (frozen RMS matches unfrozen). These already passed; they're here as coverage.

The full TestRunner suite passes: 379 doctest cases and the JUCE tests.

Note

The new warning string needs a translation pass on the app side.

Fixes Tracktion/waveform_beta#1146

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.81%. Comparing base (8896b5f) to head (e3e4801).

Files with missing lines	Patch %	Lines
...les/tracktion_engine/model/edit/tracktion_Edit.cpp	84.61%	2 Missing ⚠️
...on_engine/model/export/tracktion_Renderer.test.cpp	98.88%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #438      +/-   ##
===========================================
+ Coverage    60.64%   60.81%   +0.16%     
===========================================
  Files          568      568              
  Lines        80287    80392     +105     
  Branches     12406    12418      +12     
===========================================
+ Hits         48690    48887     +197     
+ Misses       31597    31505      -92     

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