Add bias validation to C++ WebGPU ConvTranspose implementation

Co-authored-by: guschmue <22941064+guschmue@users.noreply.github.com>

Author: Copilot

onnxruntime/core/providers/webgpu/nn/conv_transpose.cc

@@ -57,6 +57,19 @@ Status ConvTranspose<is_channels_last>::ComputeInternal(ComputeContext& context)
 
   bool has_bias = context.InputCount() > 2;
   const auto* bias = has_bias ? context.Input<Tensor>(2) : nullptr;
+  
+  // Validate bias shape if provided
+  if (has_bias) {
+    const auto& bias_shape = bias->Shape();
+    if (bias_shape.NumDimensions() != 1) {
+      return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "invalid bias: bias must be 1D tensor");
+    }
+    if (bias_shape[0] != num_output_channels) {
+      return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "invalid bias: bias size (", bias_shape[0], 
+                             ") must be equal to output channels (", num_output_channels, ")");
+    }
+  }
+  
   if (input_shape.NumDimensions() == 3 && filter_shape.NumDimensions() == 3) {
     // ConvTranspose1D
     TensorShapeVector input_shape_vector = input_shape.AsShapeVector();