Rewrite connection handling with per-device volume ownership

[d4rken]

Summary

Introduces a central AudioStreamOwnerRegistry that tracks which device group owns shared audio streams, replacing the previous broadcast-to-all approach. This ensures volumes are only applied to the correct device when multiple Bluetooth devices are connected simultaneously.

• Add AudioStreamOwnerRegistry with device grouping (Samsung Buds L+R pair within 10s window), ownership resolution (latest connection wins, fresh > bootstrap, real > speaker fallback), and stale disconnect protection
• Rewrite EventDispatcher with fast acceptance lane (ownership updated synchronously before async module launch), per-address job supersession, and displaced owner cancellation when ownership transfers
• Make VolumeDisconnectModule non-cancellable so disconnect volume saves survive fast reconnects
• Add ownership-aware filtering to VolumeUpdateModule, VolumeLockModule, VolumeRateLimiterModule, and RingerModeTransitionHandler
• Fix dashboard slider jump from percent-level-percent round-trip drift
• Fix device rename crash on Android 13+ without CDM association
• Fix ownership registry not resetting when monitoring toggle is cycled

Testing

• 116 unit tests across AudioStreamOwnerRegistryTest, EventDispatcherTest, BaseVolumeModuleTest, VolumeDisconnectModuleTest, VolumeLockModuleTest, VolumeUpdateModuleTest, VolumeRateLimiterModuleTest, and others
• Manual QA on Pixel 7a with two sets of AirPods: single/dual connect-disconnect cycles, simultaneous disconnect, ownership handoff, bootstrap recovery, enabled toggle reset