Android M1: meeting recording via foreground service

- core/recording: MeetingRecorder (AudioRecord at the device's native
  rate, WAV on disk + 60 s rolling window resampled to 16 kHz), streaming
  WavWriter, thread-safe RollingWindow, linear resampler; WavReader moved
  here from the app
- app: RecorderService (foreground, type microphone) with ongoing
  notification and StateFlow state; Record/Stop UI with timer and level
  meter; runtime permission flow; finished recordings auto-load for
  transcription
- launcher icon (mic + waveform, matching the desktop brand) and
  notification glyph
- fix real M0 bug caught by the new unit tests: WavReader parsed 16-bit
  fmt fields (audioFormat/channels/bitsPerSample) with 32-bit reads
- JVM tests: WAV round trip, native-rate header, resampler, rolling
  window — 5/5 green; assembleDebug and aapt2 APK checks pass
- validated on-device on a Fairphone 6 (Android 16): model download,
  engine load, recording and transcription all working

android/gradle/libs.versions.toml

@@ -5,6 +5,7 @@ coroutines = "1.11.0"
 coreKtx = "1.18.0"
 activityCompose = "1.13.0"
 composeBom = "2026.06.01"
+junit = "4.13.2"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
@@ -14,6 +15,7 @@ androidx-compose-ui = { group = "androidx.compose.ui", name = "ui" }
 androidx-compose-ui-tooling-preview = { group = "androidx.compose.ui", name = "ui-tooling-preview" }
 androidx-compose-material3 = { group = "androidx.compose.material3", name = "material3" }
 kotlinx-coroutines-android = { group = "org.jetbrains.kotlinx", name = "kotlinx-coroutines-android", version.ref = "coroutines" }
+junit = { group = "junit", name = "junit", version.ref = "junit" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }