🧹 refactor: simplify _platformConfiguration by extracting platform properties

[google-labs-jules]

🎯 What: The large object construction and nested switch expression in _platformConfiguration have been broken down.
💡 Why: By extracting the switch statement that extracts platform map configuration specifics (kind, emphasisStyle, showsTraffic, pointOfInterestFilter) into an extension on MKMapConfiguration, the length of the _platformConfiguration method is reduced, and the function focuses purely on assembling the PlatformMapConfiguration bundle.
✅ Verification: Verified by checking format, lint, and all test targets passing via flutter test. Exhaustiveness of the switch statement on the sealed class MKMapConfiguration is preserved.
✨ Result: Improved readability and testability without changing logic or output types.

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PR created automatically by Jules for task 13739231968334380225 started by @esenmx

[google-labs-jules]

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