Update model name placeholder in input field to reflect new formats for LLM usage, enhancing user guidance for model selection.

app.py

@@ -816,7 +816,7 @@ def main():
             else:  # Custom
                 custom_model_name = st.text_input(
                     "Model Name (litellm format)",
-                    placeholder="e.g., gpt-4o, claude-3-5-sonnet, gemini/gemini-1.5-pro",
+                    placeholder="e.g., openai/gpt-5.2, anthropic/claude-sonnet-4-5, gemini/gemini-3-pro-preview",
                     help="Enter the model name in litellm format. See [litellm documentation](https://docs.litellm.ai/docs/providers) for supported formats.",
                     key="custom_model_name",
                 )