Add release build configuration with automatic signing

- Configure release build type with minify and shrink resources
- Add signing configuration using keystore
- Use gradle.properties for secure password storage
- Add keystore to .gitignore for security

app/build.gradle.kts

@@ -20,13 +20,24 @@ android {
         }
     }
 
+    signingConfigs {
+        create("release") {
+            storeFile = file(project.properties["RELEASE_STORE_FILE"] as String? ?: "my-release.jks")
+            storePassword = project.properties["RELEASE_STORE_PASSWORD"] as String? ?: "android123"
+            keyAlias = project.properties["RELEASE_KEY_ALIAS"] as String? ?: "my-key"
+            keyPassword = project.properties["RELEASE_KEY_PASSWORD"] as String? ?: "android123"
+        }
+    }
+
     buildTypes {
         release {
-            isMinifyEnabled = false
+            isMinifyEnabled = true
+            isShrinkResources = true
             proguardFiles(
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"
             )
+            signingConfig = signingConfigs.getByName("release")
         }
     }
     compileOptions {