fix: persist download queue to survive app restart (v1.6.1)

- Download queue now persisted to SharedPreferences
- Auto-restore pending downloads on app restart
- Interrupted downloads reset to queued and auto-resumed
- singleTask launch mode to prevent app restart on share intent
- onNewIntent handler for proper intent handling
- Reverted share_plus to 10.1.4 (12.0.1 has Kotlin build issues)

android/app/src/main/AndroidManifest.xml

@@ -23,8 +23,7 @@
         <activity
             android:name=".MainActivity"
             android:exported="true"
-            android:launchMode="singleTop"
-            android:taskAffinity=""
+            android:launchMode="singleTask"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
             android:hardwareAccelerated="true"

android/app/src/main/kotlin/com/zarz/spotiflac/MainActivity.kt

@@ -1,5 +1,6 @@
 package com.zarz.spotiflac
 
+import android.content.Intent
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
 import io.flutter.plugin.common.MethodChannel
@@ -14,6 +15,12 @@ class MainActivity: FlutterActivity() {
     private val CHANNEL = "com.zarz.spotiflac/backend"
     private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Main)
 
+    override fun onNewIntent(intent: Intent) {
+        super.onNewIntent(intent)
+        // Update the intent so receive_sharing_intent can access the new data
+        setIntent(intent)
+    }
+
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)