Refactor map integration to use MapLibre instead of Mapbox

- Removed Mapbox dependencies and related configurations from settings.gradle.kts and build.gradle.kts.
- Implemented MapViewModel to manage zone data and loading state.
- Updated MapScreen to render zones using MapLibre, including loading indicators and error handling.
- Added GeoJSON generation for zone data to be displayed on the map.
- Updated libraries version to use MapLibre Compose.

app/build.gradle.kts

@@ -30,13 +30,6 @@ android {
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
 
-        // Inject Mapbox public token as a BuildConfig field
-        buildConfigField(
-            "String",
-            "MAPBOX_PUBLIC_TOKEN",
-            "\"${localProperties.getProperty("MAPBOX_PUBLIC_TOKEN", "")}\""
-        )
-
         // Backend base URL
         buildConfigField(
             "String",
@@ -121,8 +114,8 @@ dependencies {
     implementation(libs.kotlinx.serialization.json)
     implementation(libs.retrofit.kotlinx.serialization)
 
-    // Mapbox (uncomment after setting MAPBOX_DOWNLOADS_TOKEN in local.properties)
-    // implementation(libs.mapbox.maps)
+    // MapLibre (free, no API key needed)
+    implementation(libs.maplibre.compose)
 
     // Firebase (uncomment when google-services.json is added)
     // implementation(platform(libs.firebase.bom))