Add native Android app scaffold (M0): whisper.cpp engine via JNI

- android/: Gradle/Kotlin project (AGP 9.4, Compose, NDK 27.1), monorepo
  subdir as planned; whisper.cpp v1.9.3 vendored via pinned fetch script
- core/whisper: JNI wrapper (beam size, threads, language) + WhisperEngine
  Kotlin API mirroring the desktop engine contract
- app (M0 scope): in-app GGML model download from Hugging Face, engine
  load, WAV picker with resampling, on-device transcription, share sheet
- build validated: assembleDebug OK, libwhisper_jni.so + ggml packaged

android/app/build.gradle.kts

@@ -0,0 +1,43 @@
+plugins {
+    alias(libs.plugins.android.application)
+    alias(libs.plugins.kotlin.compose)
+}
+
+android {
+    namespace = "com.meetrec.android"
+    compileSdk = 36
+
+    defaultConfig {
+        applicationId = "com.meetrec.android"
+        minSdk = 29
+        targetSdk = 36
+        versionCode = 1
+        versionName = "0.1.0"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    buildFeatures {
+        compose = true
+    }
+}
+
+dependencies {
+    implementation(project(":core:whisper"))
+    implementation(libs.androidx.core.ktx)
+    implementation(libs.androidx.activity.compose)
+    implementation(platform(libs.androidx.compose.bom))
+    implementation(libs.androidx.compose.ui)
+    implementation(libs.androidx.compose.material3)
+    implementation(libs.kotlinx.coroutines.android)
+    debugImplementation(libs.androidx.compose.ui.tooling.preview)
+}