Name release APK Fabled-<version>.<build>.apk

Gradle applicationVariants hook renames the output from app-release.apk
to e.g. Fabled-26.03.01.1.apk. The correctly named file is produced at
build/app/outputs/apk/release/ and should be used for Forgejo releases.

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

android/app/build.gradle.kts

@@ -37,6 +37,14 @@ android {
             signingConfig = signingConfigs.getByName("debug")
         }
     }
+
+    applicationVariants.all {
+        val variant = this
+        outputs.all {
+            val output = this as? com.android.build.gradle.internal.api.BaseVariantOutputImpl
+            output?.outputFileName = "Fabled-${variant.versionName}.${variant.versionCode}.apk"
+        }
+    }
 }
 
 flutter {