feat: implement Android app signing setup and update .gitignore for keystore files

android/.gitignore

@@ -52,10 +52,10 @@ captures/
 # Comment next line if keeping position of elements in Navigation Editor is relevant for you
 .idea/navEditor.xml
 
-# Keystore files
+# Keystore files - NEVER commit these!
-# Uncomment the following lines if you do not want to check your keystore files in.
+*.jks
-#*.jks
+*.keystore
-#*.keystore
+keystore.properties
 
 # External native build folder generated in Android Studio 2.2 and later
 .externalNativeBuild

android/SIGNING_SETUP.md

@@ -0,0 +1,61 @@
+# Android App Signing Setup
+
+## Why This Matters
+Android requires apps to be signed with the same key for updates to work. Without proper signing, users cannot update your app - they must uninstall and reinstall, losing all data.
+
+## Setup Instructions
+
+### 1. Create a Keystore (if you don't have one)
+
+Run this command in the `android/` directory:
+
+```bash
+keytool -genkey -v -keystore paarrot-release.keystore -alias paarrot -keyalg RSA -keysize 2048 -validity 10000
+```
+
+You'll be asked for:
+- Keystore password (remember this!)
+- Key password (remember this!)  
+- Your name, organization, etc.
+
+**IMPORTANT**: Back up this keystore file and remember the passwords! If you lose either, you cannot update your app.
+
+### 2. Create keystore.properties
+
+Copy the example file:
+
+```bash
+cp keystore.properties.example keystore.properties
+```
+
+Then edit `keystore.properties` and fill in:
+- `storeFile`: path to your keystore (e.g., `paarrot-release.keystore`)
+- `storePassword`: the keystore password you set
+- `keyAlias`: the alias (e.g., `paarrot`)
+- `keyPassword`: the key password you set
+
+### 3. Verify
+
+The file `keystore.properties` should be gitignored (check `.gitignore`).
+
+### 4. Build
+
+Now your release builds will be properly signed:
+
+```bash
+cd android
+./gradlew assembleRelease
+```
+
+The signed APK will be in: `app/build/outputs/apk/release/`
+
+## Troubleshooting
+
+### "Updates not installing"
+- You're using a different keystore than the original APK
+- Solution: Use the same keystore that was used for the first release
+
+### "keystore.properties not found"
+- Normal for debug builds
+- Only needed for release builds
+- Create the file following step 2 above

android/app/build.gradle

@@ -1,9 +1,28 @@
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 
+// Load keystore properties
+def keystorePropertiesFile = rootProject.file("keystore.properties")
+def keystoreProperties = new Properties()
+if (keystorePropertiesFile.exists()) {
+    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+}
+
 android {
     namespace = "com.paarrot.app"
     compileSdk = rootProject.ext.compileSdkVersion
+    
+    signingConfigs {
+        release {
+            if (keystorePropertiesFile.exists()) {
+                storeFile file(keystoreProperties['storeFile'])
+                storePassword keystoreProperties['storePassword']
+                keyAlias keystoreProperties['keyAlias']
+                keyPassword keystoreProperties['keyPassword']
+            }
+        }
+    }
+    
     defaultConfig {
         applicationId "com.paarrot.app"
         minSdkVersion rootProject.ext.minSdkVersion
@@ -21,6 +40,9 @@ android {
         release {
             minifyEnabled false
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            if (keystorePropertiesFile.exists()) {
+                signingConfig signingConfigs.release
+            }
         }
     }
     applicationVariants.all { variant ->

android/keystore.properties.example

@@ -0,0 +1,14 @@
+# Copy this file to keystore.properties and fill in your actual values
+# NEVER commit keystore.properties to git!
+
+# Path to your keystore file (relative to android/ directory)
+storeFile=paarrot-release.keystore
+
+# Keystore password
+storePassword=your_keystore_password_here
+
+# Key alias
+keyAlias=paarrot
+
+# Key password
+keyPassword=your_key_password_here