Apple Silicon simulator builds fail because MLImage and MLKit contain
device-labelled ARM64 objects.
Enable the Flutter ML Kit package's upstream compatibility helper, which
restores device labels for iPhone builds. This preserves the MLKit-based
functionality (avatar background removal) and complements the
notification-extension linker isolation in #7187.
Adds a complete iOS simulator build to CI to catch this build
regression.
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Signed-off-by: Tom Brow <tomb@block.xyz>
