Fix multi-device EQ auto-switching by calling obtenerDispositivoActual()
during cargarPersistido() to seed the initial device ID. Add device
management modal with rename support, EQ preset editing, and connection
status indicator. Translate device UI keys to all 13 locales.
Introduce multi-device EQ support allowing each audio output device
(built-in speaker, wired, USB, individual Bluetooth by MAC) to have
its own equalizer preset, combined with existing per-station presets
for a full station×device matrix.
- Add DispositivoAudio model and ServicioDispositivoAudio interface
- Add Android platform channel (AudioDeviceCallback) for device detection
- Add iOS AudioDevicesPlugin (AVAudioSession route tracking)
- Extend ServicioEcualizador with device and matrix persistence keys
- Implement 4-level resolution: matrix > station > device > global
- Add advanced EQ settings section with feature toggle (off by default)
- Extend export/import to v3 with backward compatibility
- 184 tests passing, zero analyzer issues
- New ServicioExportImport owns the v2 backup envelope, pretty JSON encode and graceful decode; byte-compatible with existing exports, locked by a round-trip test
- pantalla_ajustes delegates backup serialization to the service (inline jsonDecode/jsonEncode removed)
- New EstadoEcualizador ChangeNotifier owns all EQ state and persistence (principal/current/per-station presets, active flag), exposed via its own provider so EQ changes no longer rebuild EstadoRadio consumers
- EstadoRadio slims down ~210 lines and keeps 15 delegating compat members marked TODO(S4b) for the next slice to remove
- Player EQ toggle rewired to the new provider to avoid going stale
- 4 new tests (103 total green), flutter analyze clean