Add release build

Android.mk

@@ -0,0 +1,16 @@
+LOCAL_PATH := $(my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE := catflipscreen
+LOCAL_SRC_FILES := app/release/app-release.apk
+LOCAL_MODULE_CLASS := APPS
+LOCAL_MODULE_SUFFIX := .apk
+LOCAL_BUILT_MODULE_STEM := package.apk
+LOCAL_CERTIFICATE := platform
+LOCAL_PRIVILEGED_MODULE := true
+LOCAL_ENFORCE_USES_LIBRARIES := false
+
+include $(BUILD_PREBUILT)
+

app/release/output-metadata.json

@@ -0,0 +1,20 @@
+{
+  "version": 3,
+  "artifactType": {
+    "type": "APK",
+    "kind": "Directory"
+  },
+  "applicationId": "net.mezimmah.catflipscreen",
+  "variantName": "release",
+  "elements": [
+    {
+      "type": "SINGLE",
+      "filters": [],
+      "attributes": [],
+      "versionCode": 1,
+      "versionName": "1.0",
+      "outputFile": "app-release.apk"
+    }
+  ],
+  "elementType": "File"
+}