Add Gradle build script with signing

src-tauri/gen/android/app/build.gradle.kts

@@ -0,0 +1,86 @@
+import java.util.Properties
+import java.io.FileInputStream
+
+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+    id("rust")
+}
+
+val tauriProperties = Properties().apply {
+    val propFile = file("tauri.properties")
+    if (propFile.exists()) {
+        propFile.inputStream().use { load(it) }
+    }
+}
+
+android {
+    compileSdk = 34
+    namespace = "de.mathebau.bkbh"
+    defaultConfig {
+        manifestPlaceholders["usesCleartextTraffic"] = "false"
+        applicationId = "de.mathebau.bkbh"
+        minSdk = 24
+        targetSdk = 34
+        versionCode = tauriProperties.getProperty("tauri.android.versionCode", "1").toInt()
+        versionName = tauriProperties.getProperty("tauri.android.versionName", "1.0")
+    }
+    signingConfigs {
+        create("release") {
+            val keystorePropertiesFile = rootProject.file("keystore.properties")
+            val keystoreProperties = Properties()
+            if (keystorePropertiesFile.exists()) {
+                keystoreProperties.load(FileInputStream(keystorePropertiesFile))
+            }
+
+            keyAlias = keystoreProperties["keyAlias"] as String
+            keyPassword = keystoreProperties["password"] as String
+            storeFile = file(keystoreProperties["storeFile"] as String)
+            storePassword = keystoreProperties["password"] as String
+        }
+    }
+    buildTypes {
+        getByName("debug") {
+            signingConfig = signingConfigs.getByName("release")
+            manifestPlaceholders["usesCleartextTraffic"] = "true"
+            isDebuggable = true
+            isJniDebuggable = true
+            isMinifyEnabled = false
+            packaging {                jniLibs.keepDebugSymbols.add("*/arm64-v8a/*.so")
+                jniLibs.keepDebugSymbols.add("*/armeabi-v7a/*.so")
+                jniLibs.keepDebugSymbols.add("*/x86/*.so")
+                jniLibs.keepDebugSymbols.add("*/x86_64/*.so")
+            }
+        }
+        getByName("release") {
+            signingConfig = signingConfigs.getByName("release")
+            isMinifyEnabled = true
+            proguardFiles(
+                *fileTree(".") { include("**/*.pro") }
+                    .plus(getDefaultProguardFile("proguard-android-optimize.txt"))
+                    .toList().toTypedArray()
+            )
+        }
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+    buildFeatures {
+        buildConfig = true
+    }
+}
+
+rust {
+    rootDirRel = "../../../"
+}
+
+dependencies {
+    implementation("androidx.webkit:webkit:1.6.1")
+    implementation("androidx.appcompat:appcompat:1.6.1")
+    implementation("com.google.android.material:material:1.8.0")
+    testImplementation("junit:junit:4.13.2")
+    androidTestImplementation("androidx.test.ext:junit:1.1.4")
+    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.0")
+}
+
+apply(from = "tauri.build.gradle.kts")