Fix LSTM clipping before h activation (Issue #27224)

- Add clipping of Ct before applying h activation function
- Complies with ONNX spec requirement for clipping input of activations
- Equation: Ht = ot (.) h(clip(Ct)) instead of Ht = ot (.) h(Ct)

Author: chaya2350

onnxruntime/core/providers/cpu/rnn/uni_directional_lstm.cc

@@ -578,7 +578,14 @@ void UniDirectionalLstm<T>::GateComputations(
     float* pC_prev_clipped = SafeRawPointer<T>(C_prev_clipped + b * hidden_size_, C_prev_clipped_end, hidden_size_);
 #endif
 
-    activation_h_.func(pC_cur, pC_prev_clipped, po, pH, hidden_size_, activation_h_.alpha, activation_h_.beta);
+    // Clip Ct before applying h activation function (per ONNX spec)
+    // Copy Ct to temporary buffer and apply clipping
+    for (int i = 0; i < hidden_size_; ++i) {
+      pC_prev_clipped[i] = pC_cur[i];
+    }
+    clip_with_bias_ptr_(clip_, nullptr, pC_prev_clipped, hidden_size_);
+
+    activation_h_.func(pC_prev_clipped, pC_prev_clipped, po, pH, hidden_size_, activation_h_.alpha, activation_h_.beta);
 
     // DumpMatrix("H" + row_str, pH, 1, hidden_size_);
   }