Fix Gradio 5.x compatibility: use messages format for Chatbot

Change Chatbot type from 'tuples' to 'messages' and update all
history handling to use dict format with role/content keys.
This resolves the TypeError in gradio_client/utils.py.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app.py

@@ -882,7 +882,7 @@ def create_app():
                     show_label=True,
                     elem_id="chatbot",
                     bubble_full_width=False,
-                    type="tuples"
+                    type="messages"
                 )
 
                 # Needs selector (hidden until stage 5)
@@ -1004,7 +1004,10 @@ def create_app():
 
             if stage == 5 and not sel_needs:
                 bot_response = "Please take a moment to select your needs from the list above, then click 'Confirm My Needs' to continue."
-                history = history + [[message, bot_response]]
+                history = history + [
+                    {"role": "user", "content": message},
+                    {"role": "assistant", "content": bot_response}
+                ]
                 return (
                     history, "", stage, session, sel_needs,
                     f"{stage}/13: {STAGE_NAMES[stage]}",
@@ -1021,7 +1024,10 @@ def create_app():
             )
 
             if error:
-                history = history + [[message, error]]
+                history = history + [
+                    {"role": "user", "content": message},
+                    {"role": "assistant", "content": error}
+                ]
                 return (
                     history, "", stage, session, sel_needs,
                     f"{stage}/13: {STAGE_NAMES[stage]}",
@@ -1030,9 +1036,14 @@ def create_app():
                 )
 
             if message != "continue":
-                history = history + [[message, response]]
+                history = history + [
+                    {"role": "user", "content": message},
+                    {"role": "assistant", "content": response}
+                ]
             else:
-                history = history + [[None, response]]
+                history = history + [
+                    {"role": "assistant", "content": response}
+                ]
 
             show_needs = (next_stage == 5)
 
@@ -1078,7 +1089,7 @@ def create_app():
             if not all_selected:
                 return (
                     all_selected,
-                    history + [[None, "Please select at least one need before continuing."]],
+                    history + [{"role": "assistant", "content": "Please select at least one need before continuing."}],
                     stage,
                     session
                 )
@@ -1092,7 +1103,10 @@ def create_app():
                 True
             )
 
-            history = history + [[f"Selected needs: {', '.join(all_selected)}", response]]
+            history = history + [
+                {"role": "user", "content": f"Selected needs: {', '.join(all_selected)}"},
+                {"role": "assistant", "content": response}
+            ]
 
             return all_selected, history, next_stage, updated_session