feat: Add MonitoredDevice facade and DeviceMonitor merge point

MonitoredDevice unifies BLE and AAP data sources with dynamic resolution.

DeviceMonitor combines PodMonitor + AapConnectionManager into a single Flow.

To be renamed to PodDevice/PodMonitor when the old types are renamed to BlePodSnapshot/BlePodMonitor.

app/src/main/java/eu/darken/capod/monitor/core/DeviceMonitor.kt

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+package eu.darken.capod.monitor.core
+
+import eu.darken.capod.pods.core.apple.protocol.aap.AapConnectionManager
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.combine
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * Single merge point: combines BLE scan data ([PodMonitor]) with AAP connection data
+ * ([AapConnectionManager]) into unified [MonitoredDevice] objects.
+ *
+ * ViewModels should observe [devices] instead of accessing PodMonitor directly.
+ *
+ * TODO: Rename to PodMonitor once old PodMonitor is renamed to BlePodMonitor.
+ */
+@Singleton
+class DeviceMonitor @Inject constructor(
+    private val podMonitor: PodMonitor,
+    private val aapManager: AapConnectionManager,
+) {
+    val devices: Flow<List<MonitoredDevice>> = podMonitor.devices
+        .combine(aapManager.allStates) { pods, aapStates ->
+            pods.map { pod ->
+                MonitoredDevice(
+                    ble = pod,
+                    aap = aapStates[pod.address],
+                )
+            }
+        }
+}

app/src/main/java/eu/darken/capod/monitor/core/MonitoredDevice.kt

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+package eu.darken.capod.monitor.core
+
+import eu.darken.capod.common.bluetooth.BluetoothAddress
+import eu.darken.capod.pods.core.DualPodDevice
+import eu.darken.capod.pods.core.HasCase
+import eu.darken.capod.pods.core.HasEarDetectionDual
+import eu.darken.capod.pods.core.PodDevice
+import eu.darken.capod.pods.core.SinglePodDevice
+import eu.darken.capod.pods.core.apple.DualApplePods
+import eu.darken.capod.pods.core.apple.protocol.aap.AapPodState
+import eu.darken.capod.pods.core.apple.protocol.aap.AapSetting
+
+/**
+ * Unified device facade combining BLE scan data and AAP connection data.
+ * All properties are dynamically resolved from the best available source.
+ * Consumers don't need to know whether data came from BLE or AAP.
+ *
+ * TODO: Rename to PodDevice once old PodDevice interface is renamed to BlePodSnapshot.
+ */
+data class MonitoredDevice(
+    internal val ble: PodDevice?,
+    internal val aap: AapPodState?,
+) {
+    // Identity
+    val model: PodDevice.Model get() = ble?.model ?: PodDevice.Model.UNKNOWN
+    val address: BluetoothAddress? get() = ble?.address
+
+    // Capabilities from Model.Features
+    val hasCase: Boolean get() = model.features.hasCase
+    val hasDualPods: Boolean get() = model.features.hasDualPods
+    val hasEarDetection: Boolean get() = model.features.hasEarDetection
+    val hasAncControl: Boolean get() = model.features.hasAncControl
+
+    // Battery — best available source
+    val batteryLeft: Float?
+        get() = (ble as? DualPodDevice)?.batteryLeftPodPercent
+
+    val batteryRight: Float?
+        get() = (ble as? DualPodDevice)?.batteryRightPodPercent
+
+    val batteryCase: Float?
+        get() = (ble as? HasCase)?.batteryCasePercent
+
+    val batteryHeadset: Float?
+        get() = (ble as? SinglePodDevice)?.batteryHeadsetPercent
+
+    // State
+    val isLeftInEar: Boolean?
+        get() = (ble as? HasEarDetectionDual)?.isLeftPodInEar
+
+    val isRightInEar: Boolean?
+        get() = (ble as? HasEarDetectionDual)?.isRightPodInEar
+
+    val caseLidState: DualApplePods.LidState?
+        get() = (ble as? DualApplePods)?.caseLidState
+
+    // AAP controls
+    val ancMode: AapSetting.AncMode?
+        get() = aap?.setting()
+
+    val isAapConnected: Boolean get() = aap != null
+}

app/src/test/java/eu/darken/capod/monitor/core/MonitoredDeviceTest.kt

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+package eu.darken.capod.monitor.core
+
+import eu.darken.capod.pods.core.PodDevice
+import eu.darken.capod.pods.core.apple.DualApplePods
+import eu.darken.capod.pods.core.apple.protocol.aap.AapConnectionState
+import eu.darken.capod.pods.core.apple.protocol.aap.AapPodState
+import eu.darken.capod.pods.core.apple.protocol.aap.AapSetting
+import eu.darken.capod.pods.core.apple.protocol.aap.AncModeValue
+import io.kotest.matchers.nulls.shouldBeNull
+import io.kotest.matchers.nulls.shouldNotBeNull
+import io.kotest.matchers.shouldBe
+import io.mockk.every
+import io.mockk.mockk
+import org.junit.jupiter.api.Test
+import testhelpers.BaseTest
+
+class MonitoredDeviceTest : BaseTest() {
+
+    private fun mockDualPod(
+        model: PodDevice.Model = PodDevice.Model.AIRPODS_PRO3,
+        leftBattery: Float? = 0.8f,
+        rightBattery: Float? = 0.9f,
+        caseBattery: Float? = 0.5f,
+    ): PodDevice {
+        // DualApplePods implements DualPodDevice + HasCase + other interfaces
+        return mockk<DualApplePods>(relaxed = true) {
+            every { this@mockk.model } returns model
+            every { batteryLeftPodPercent } returns leftBattery
+            every { batteryRightPodPercent } returns rightBattery
+            every { batteryCasePercent } returns caseBattery
+        }
+    }
+
+    @Test
+    fun `BLE-only device exposes battery from BLE`() {
+        val device = MonitoredDevice(ble = mockDualPod(leftBattery = 0.8f), aap = null)
+        device.batteryLeft shouldBe 0.8f
+        device.isAapConnected shouldBe false
+    }
+
+    @Test
+    fun `capabilities come from model features`() {
+        val device = MonitoredDevice(
+            ble = mockDualPod(model = PodDevice.Model.AIRPODS_PRO3),
+            aap = null,
+        )
+        device.hasDualPods shouldBe true
+        device.hasCase shouldBe true
+        device.hasEarDetection shouldBe true
+        device.hasAncControl shouldBe true
+    }
+
+    @Test
+    fun `Beats Solo 3 has no dual pods or case`() {
+        val device = MonitoredDevice(
+            ble = mockk(relaxed = true) { every { model } returns PodDevice.Model.BEATS_SOLO_3 },
+            aap = null,
+        )
+        device.hasDualPods shouldBe false
+        device.hasCase shouldBe false
+    }
+
+    @Test
+    fun `AAP settings are available when connected`() {
+        val aap = AapPodState(
+            connectionState = AapConnectionState.READY,
+            settings = mapOf(
+                AapSetting.AncMode::class to AapSetting.AncMode(
+                    AncModeValue.TRANSPARENCY,
+                    listOf(AncModeValue.ON, AncModeValue.TRANSPARENCY, AncModeValue.ADAPTIVE),
+                ),
+            ),
+        )
+        val device = MonitoredDevice(ble = mockDualPod(), aap = aap)
+        device.isAapConnected shouldBe true
+        device.ancMode.shouldNotBeNull()
+        device.ancMode!!.current shouldBe AncModeValue.TRANSPARENCY
+    }
+
+    @Test
+    fun `ANC mode is null when not AAP connected`() {
+        val device = MonitoredDevice(ble = mockDualPod(), aap = null)
+        device.ancMode.shouldBeNull()
+    }
+
+    @Test
+    fun `null BLE gives UNKNOWN model`() {
+        val device = MonitoredDevice(ble = null, aap = null)
+        device.model shouldBe PodDevice.Model.UNKNOWN
+    }
+}