Add version.properties and read version in build.gradle

Single source of truth: bump VERSION_NAME/VERSION_CODE in version.properties
to release a new version. BuildConfig.VERSION_NAME exposed to the app.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/build.gradle.kts

@@ -1,3 +1,5 @@
+import java.util.Properties
+
 plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.kotlin.android)
@@ -7,6 +9,10 @@ plugins {
     alias(libs.plugins.ksp)
 }
 
+val versionProps = Properties().apply {
+    load(rootProject.file("version.properties").inputStream())
+}
+
 android {
     namespace = "com.syncflow"
     compileSdk = 34
@@ -15,8 +21,8 @@ android {
         applicationId = "com.syncflow"
         minSdk = 26
         targetSdk = 35
-        versionCode = 1
-        versionName = "1.0.0"
+        versionCode = versionProps["VERSION_CODE"].toString().toInt()
+        versionName = versionProps["VERSION_NAME"].toString()
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
 
         // Placeholder — replace with real keys before release