fix: remove hard block on empty context for Custom vertical — make context optional

chat_interface.py

@@ -5268,13 +5268,8 @@ def create_chat_tab(chat_controller_state, settings, current_stage, current_mode
             hide_welcome = gr.update(visible=False)
 
             if is_custom:
-                # Custom vertical: context IS the use case; function dropdown is ignored
-                use_case_str = (additional_info or "").strip()
-                if not use_case_str:
-                    history = history or []
-                    history.append(("GO", "❌ Please describe your use case in the Context field when using Custom vertical."))
-                    yield (controller, gr.update(value=history, visible=True), stage, model, company, usecase, get_progress_html(stage), hide_welcome)
-                    return
+                # Custom vertical: context drives the use case; function dropdown is ignored
+                use_case_str = (additional_info or "").strip() or "Custom Demo"
                 controller.vertical = None
                 controller.function = None
                 controller.use_case_config = get_use_case_config("Generic", "Generic")