Release cleanup: remove unused state, harden service, add proguard rules

- Remove unused serviceRunning state variable
- Guard unregisterReceiver against double-call
- Add proguard rules for OkHttp, Coroutines, Play Services, WorkManager
- Remove empty drawable directory

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

app/proguard-rules.pro

@@ -1,21 +1,14 @@
-# Add project specific ProGuard rules here.
-# You can control the set of applied configuration files using the
-# proguardFiles setting in build.gradle.
-#
-# For more details, see
-#   http://developer.android.com/guide/developing/tools/proguard.html
+# OkHttp
+-dontwarn okhttp3.**
+-dontwarn okio.**
+-keep class okhttp3.** { *; }
 
-# If your project uses WebView with JS, uncomment the following
-# and specify the fully qualified class name to the JavaScript interface
-# class:
-#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
-#   public *;
-#}
+# Coroutines
+-dontwarn kotlinx.coroutines.**
 
-# Uncomment this to preserve the line number information for
-# debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
+# Play Services
+-keep class com.google.android.gms.** { *; }
 
-# If you keep the line number information, uncomment this to
-# hide the original source file name.
-#-renamesourcefileattribute SourceFile
+# WorkManager
+-keep class * extends androidx.work.Worker
+-keep class * extends androidx.work.CoroutineWorker

app/src/main/java/com/example/helios_location_finder/ListenerService.kt

@@ -39,8 +39,10 @@ class ListenerService : Service() {
     }
 
     override fun onDestroy() {
+        try {
             unregisterReceiver(receiver)
-        Log.d(TAG, "Listener service stopped, receiver unregistered")
+        } catch (_: IllegalArgumentException) { }
+        Log.d(TAG, "Listener service stopped")
         super.onDestroy()
     }
 

app/src/main/java/com/example/helios_location_finder/MainActivity.kt

@@ -50,7 +50,6 @@ class MainActivity : ComponentActivity() {
 
     private val foregroundGranted = mutableStateOf(false)
     private val backgroundGranted = mutableStateOf(false)
-    private val serviceRunning = mutableStateOf(false)
 
     private val foregroundPermissionLauncher = registerForActivityResult(
         ActivityResultContracts.RequestMultiplePermissions()
@@ -154,7 +153,6 @@ class MainActivity : ComponentActivity() {
             }
         }
         ListenerService.start(this)
-        serviceRunning.value = true
     }
 }