capgo and adk autoupdates. card tags

mobile-client/android/app/build.gradle

@@ -1,5 +1,20 @@
 apply plugin: 'com.android.application'
 
+// ---- Cardy: versioning and signing ----
+
+// versionCode from the build time (UTC): yyDDDHHmm (year, day of year, time), e.g. 262721430.
+// Grows with every build and stays below Android's limit (2100000000) until 2099.
+// Override with -PcardyVersionCode=... (the APK publishing script passes the value it records).
+def cardyVersionCode = project.findProperty('cardyVersionCode') ?: new Date().format('yyDDDHHmm', TimeZone.getTimeZone('UTC'))
+def cardyVersionName = project.findProperty('cardyVersionName') ?: '1.0'
+
+// Release key: android/keystore.properties (not in git) with storeFile, storePassword, keyAlias, keyPassword.
+// Debug builds use the same key so that Android Studio builds and published APKs can replace each other.
+def keystoreProps = new Properties()
+def keystoreFile = rootProject.file('keystore.properties')
+if (keystoreFile.exists()) keystoreFile.withInputStream { keystoreProps.load(it) }
+def hasReleaseKey = ['storeFile', 'storePassword', 'keyAlias', 'keyPassword'].every { keystoreProps.getProperty(it)?.trim() }
+
 android {
     namespace = "com.aggtaa.cardy"
     compileSdk = rootProject.ext.compileSdkVersion
@@ -7,8 +22,8 @@ android {
         applicationId "com.aggtaa.cardy"
         minSdkVersion rootProject.ext.minSdkVersion
         targetSdkVersion rootProject.ext.targetSdkVersion
-        versionCode 1
-        versionName "1.0"
+        versionCode cardyVersionCode as Integer
+        versionName cardyVersionName
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         aaptOptions {
              // Files and dirs to omit from the packaged assets dir, modified to accommodate modern web apps.
@@ -16,14 +31,32 @@ android {
             ignoreAssetsPattern = '!.svn:!.git:!.ds_store:!*.scc:.*:!CVS:!thumbs.db:!picasa.ini:!*~'
         }
     }
+    signingConfigs {
+        if (hasReleaseKey) {
+            cardy {
+                storeFile file(keystoreProps.getProperty('storeFile').trim())
+                storePassword keystoreProps.getProperty('storePassword')
+                keyAlias keystoreProps.getProperty('keyAlias').trim()
+                keyPassword keystoreProps.getProperty('keyPassword')
+            }
+        }
+    }
     buildTypes {
         release {
             minifyEnabled false
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            if (hasReleaseKey) signingConfig signingConfigs.cardy
+        }
+        debug {
+            if (hasReleaseKey) signingConfig signingConfigs.cardy
         }
     }
 }
 
+if (!hasReleaseKey) {
+    logger.warn('Cardy: android/keystore.properties is missing or incomplete: debug builds use the debug key, release builds are unsigned.')
+}
+
 repositories {
     flatDir{
         dirs '../capacitor-cordova-android-plugins/src/main/libs', 'libs'