Improve mouse movement performance

[enaboapps]

Summary

Optimize the Switchify PC mouse movement path for smoother high-frequency control from Android.

Scope

• Use relative Windows input for mouse movement.
• Reduce per-command persistence overhead in auth validation.
• Keep Bluetooth command processing off the WPF dispatcher where possible.
• Reduce cursor overlay work during continuous movement.

Validation

• Run the C# restore/build/test checks.
• Smoke test Bluetooth mouse movement and core input commands on Windows.