Gate Cronet engine behind enable_quic (default off)

Cronet bypasses the OkHttp DNS/SSL stack and would nullify the
anti-DPI hooks. enable_quic is the effective engine switch.

app/src/main/kotlin/com/hippo/ehviewer/EhApplication.kt

@@ -219,7 +219,7 @@ class EhApplication : Application(), SingletonImageLoader.Factory {
             private set
 
         val ktorClient by lazy {
-            if (isCronetAvailable && Settings.enableCronet.value) {
+            if (isCronetAvailable && Settings.enableQuic.value) {
                 HttpClient(Cronet) {
                     engine { configureClient(Settings.enableQuic.value) }
                     configureCommon()

app/src/main/kotlin/com/hippo/ehviewer/Settings.kt

@@ -111,7 +111,7 @@ object Settings : DataStorePreferences(null) {
     val saveCrashLog = boolPref("save_crash_log", true)
     val readCacheSize = intPref("read_cache_size_2", 640)
     val enableCronet = boolPref("enable_cronet", true)
-    val enableQuic = boolPref("enable_quic", true)
+    val enableQuic = boolPref("enable_quic", false)
     val hardwareBitmapThreshold = intPref("hardware_bitmap_threshold", 16384)
     val preloadThumbAggressively = boolPref("preload_thumb_aggressively", false)
     val animateItems = boolPref("animate_items", true)