fix(interop): resolve native resource leaks in GTK and WebKit interop

Fix critical memory leaks identified in architecture review: Add signal handler disconnection in WebKitNative (load-changed and script-dialog signals now properly cleaned up), implement GTK idle callback cleanup with automatic removal on completion, add dlclose() calls for WebKit library handles, track GTK signal IDs in GtkSkiaSurfaceWidget for proper disposal. Replace empty catch blocks in GestureManager with logged exception handling. Add WebKitNative.Cleanup() and GtkNative.ClearCallbacks() methods for application shutdown.

Native/WebKitNative.cs

@@ -98,6 +98,8 @@ internal static class WebKitNative
 
     private static readonly Dictionary<IntPtr, LoadChangedCallback> _loadChangedCallbacks = new Dictionary<IntPtr, LoadChangedCallback>();
     private static readonly Dictionary<IntPtr, ScriptDialogCallback> _scriptDialogCallbacks = new Dictionary<IntPtr, ScriptDialogCallback>();
+    private static readonly Dictionary<IntPtr, ulong> _loadChangedSignalIds = new Dictionary<IntPtr, ulong>();
+    private static readonly Dictionary<IntPtr, ulong> _scriptDialogSignalIds = new Dictionary<IntPtr, ulong>();
 
     /// <summary>
     /// Event raised when a JavaScript dialog (alert, confirm, prompt) is requested.
@@ -115,9 +117,15 @@ internal static class WebKitNative
     [DllImport("libdl.so.2")]
     private static extern IntPtr dlsym(IntPtr handle, string symbol);
 
+    [DllImport("libdl.so.2")]
+    private static extern int dlclose(IntPtr handle);
+
     [DllImport("libdl.so.2")]
     private static extern IntPtr dlerror();
 
+    [DllImport("libgobject-2.0.so.0")]
+    private static extern void g_signal_handler_disconnect(IntPtr instance, ulong handlerId);
+
     public static bool Initialize()
     {
         if (_initialized)
@@ -302,11 +310,18 @@ internal static class WebKitNative
             return 0uL;
         }
         _loadChangedCallbacks[webView] = callback;
-        return _gSignalConnectData(webView, "load-changed", callback, IntPtr.Zero, IntPtr.Zero, 0);
+        ulong signalId = _gSignalConnectData(webView, "load-changed", callback, IntPtr.Zero, IntPtr.Zero, 0);
+        _loadChangedSignalIds[webView] = signalId;
+        return signalId;
     }
 
     public static void DisconnectLoadChanged(IntPtr webView)
     {
+        if (_loadChangedSignalIds.TryGetValue(webView, out ulong signalId) && signalId != 0)
+        {
+            g_signal_handler_disconnect(webView, signalId);
+            _loadChangedSignalIds.Remove(webView);
+        }
         _loadChangedCallbacks.Remove(webView);
     }
 
@@ -322,11 +337,18 @@ internal static class WebKitNative
             return 0uL;
         }
         _scriptDialogCallbacks[webView] = callback;
-        return _gSignalConnectData(webView, "script-dialog", callback, IntPtr.Zero, IntPtr.Zero, 0);
+        ulong signalId = _gSignalConnectData(webView, "script-dialog", callback, IntPtr.Zero, IntPtr.Zero, 0);
+        _scriptDialogSignalIds[webView] = signalId;
+        return signalId;
     }
 
     public static void DisconnectScriptDialog(IntPtr webView)
     {
+        if (_scriptDialogSignalIds.TryGetValue(webView, out ulong signalId) && signalId != 0)
+        {
+            g_signal_handler_disconnect(webView, signalId);
+            _scriptDialogSignalIds.Remove(webView);
+        }
         _scriptDialogCallbacks.Remove(webView);
     }
 
@@ -377,4 +399,29 @@ internal static class WebKitNative
     {
         _webkitScriptDialogPromptSetText?.Invoke(dialog, text);
     }
+
+    /// <summary>
+    /// Cleans up native library handles. Call on application shutdown.
+    /// </summary>
+    public static void Cleanup()
+    {
+        _loadChangedCallbacks.Clear();
+        _scriptDialogCallbacks.Clear();
+        _loadChangedSignalIds.Clear();
+        _scriptDialogSignalIds.Clear();
+
+        if (_gobjectHandle != IntPtr.Zero)
+        {
+            dlclose(_gobjectHandle);
+            _gobjectHandle = IntPtr.Zero;
+        }
+
+        if (_handle != IntPtr.Zero)
+        {
+            dlclose(_handle);
+            _handle = IntPtr.Zero;
+        }
+
+        _initialized = false;
+    }
 }