feat: implement Android BLE SDK with demo app

Complete Android port of duooomi-ios-sdk with 1:1 API parity.
Includes SDK library module and Jetpack Compose demo app.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

demo/build.gradle.kts

@@ -0,0 +1,49 @@
+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "com.duooomi.ble.demo"
+    compileSdk = 34
+
+    defaultConfig {
+        applicationId = "com.duooomi.ble.demo"
+        minSdk = 26
+        targetSdk = 34
+        versionCode = 1
+        versionName = "1.0"
+    }
+
+    buildFeatures {
+        compose = true
+    }
+
+    composeOptions {
+        kotlinCompilerExtensionVersion = "1.5.8"
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    kotlinOptions {
+        jvmTarget = "17"
+    }
+}
+
+dependencies {
+    implementation(project(":sdk"))
+
+    // Compose
+    val composeBom = platform("androidx.compose:compose-bom:2024.06.00")
+    implementation(composeBom)
+    implementation("androidx.compose.ui:ui")
+    implementation("androidx.compose.material3:material3")
+    implementation("androidx.compose.ui:ui-tooling-preview")
+    implementation("androidx.activity:activity-compose:1.8.2")
+    implementation("androidx.lifecycle:lifecycle-runtime-compose:2.7.0")
+
+    debugImplementation("androidx.compose.ui:ui-tooling")
+}