Migrate Android Gradle config to plugins { } DSL using Flutter‑recommended approach (#18)

## Summary by CodeRabbit

- **Chores**
- Updated and simplified Android build configuration, including SDK and
language version adjustments, dependency reorganization, and removal of
certain test and build options.
## Walkthrough

The Gradle build script for the Android project was simplified by
removing buildscript and repository declarations, adjusting SDK and
Java/Kotlin versions, modifying source set and test configurations,
updating the version string, and reorganizing dependencies. No changes
were made to public code entities; all changes are limited to build
configuration.

## Changes

| File(s) | Change Summary |

|--------------------------|-----------------------------------------------------------------------------------------------------------------|
| android/build.gradle | Removed buildscript and allprojects blocks,
adjusted SDK and language versions, updated version, reorganized
dependencies, modified source sets and test configuration, added
lintOptions. |

---------

Co-authored-by: martins <me@martinslaucis.lv>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: 3 people

android/build.gradle

@@ -1,69 +1,39 @@
 group = "io.pnta.pnta_flutter"
-version = "1.0-SNAPSHOT"
+version = "1.0.0"
 
-buildscript {
-    ext.kotlin_version = "1.8.22"
-    repositories {
-        google()
-        mavenCentral()
-    }
-
-    dependencies {
-        classpath("com.android.tools.build:gradle:8.2.1")
-        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version")
-        classpath("com.google.gms:google-services:4.4.1")
-    }
+plugins {
+    id "com.android.library"
+    id "org.jetbrains.kotlin.android"
 }
-
-allprojects {
-    repositories {
-        google()
-        mavenCentral()
-    }
-}
-
-apply plugin: "com.android.library"
-apply plugin: "kotlin-android"
-
 android {
-    namespace = "io.pnta.pnta_flutter"
-
-    compileSdk = 35
-
-    compileOptions {
-        sourceCompatibility = JavaVersion.VERSION_11
-        targetCompatibility = JavaVersion.VERSION_11
-    }
-
-    kotlinOptions {
-        jvmTarget = JavaVersion.VERSION_11
+  
+    compileSdkVersion 34
+    
+    if (project.android.hasProperty("namespace")) {
+        namespace = "io.pnta.pnta_flutter"
     }
 
     sourceSets {
         main.java.srcDirs += "src/main/kotlin"
-        test.java.srcDirs += "src/test/kotlin"
     }
 
-    defaultConfig {
-        minSdk = 21
+    kotlinOptions {
+        jvmTarget = "1.8"
     }
 
-    dependencies {
-        testImplementation("org.jetbrains.kotlin:kotlin-test")
-        testImplementation("org.mockito:mockito-core:5.0.0")
-        implementation 'com.google.firebase:firebase-messaging:23.4.1'
-        implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3'
+    defaultConfig {
+        minSdkVersion 21
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
-    testOptions {
-        unitTests.all {
-            useJUnitPlatform()
-
-            testLogging {
-               events "passed", "skipped", "failed", "standardOut", "standardError"
-               outputs.upToDateWhen {false}
-               showStandardStreams = true
-            }
-        }
+    lintOptions {
+        disable 'InvalidPackage'
     }
 }
+
+dependencies {
+    implementation 'com.google.firebase:firebase-messaging:23.4.1'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3'
+    testImplementation 'org.jetbrains.kotlin:kotlin-test'
+    testImplementation 'org.mockito:mockito-core:5.0.0'
+}