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/core/recording/build.gradle.kts

@@ -0,0 +1,23 @@
+plugins {
+    alias(libs.plugins.android.library)
+}
+
+android {
+    namespace = "com.meetrec.core.recording"
+    compileSdk = 36
+
+    defaultConfig {
+        minSdk = 29
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+}
+
+dependencies {
+    // WavWriter/WavReader/RollingWindow/resampler are pure Kotlin and unit
+    // tested on the JVM; MeetingRecorder needs a device (AudioRecord).
+    testImplementation(libs.junit)
+}