fix: resolve emulator crash - thread safety and icon fallback

- NativeSearch: move onResult/onError callbacks outside withContext(Dispatchers.IO) to prevent CalledFromWrongThreadException
- SearchStrategy: change callback types to suspend to enable proper coroutine chaining
- SearchCoordinator: remove leaked CoroutineScope, rely on suspend callback chaining for fallback flow
- Resources: add mipmap-hdpi/mdpi/xhdpi/xxhdpi icon fallbacks for API < 26 devices

.gitignore

@@ -0,0 +1,16 @@
+*.iml
+.gradle
+/local.properties
+/.idea
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties
+/app/build
+/app/release
+*.apk
+*.aab
+*.jks
+*.keystore