fix: merge context + topic into single field — one clear purpose

- Removed separate 'topic' field from BipolarTriggerRequest model
- Removed topic parameter from force_trigger_argument, force_trigger_argument_from_message_id, and run_argument
- trigger_context now doubles as the argument theme: if provided by user, it becomes the topic;
  if blank, a random topic is selected from the rotation pool
- Web UI: replaced two confusing fields (Context + Topic) with one clear field labeled
  'What should they argue about? (optional)' with a plain-English description
- JS: removed topic field reference, context.trim() ensures empty strings aren't sent

bot/routes/bipolar_mode.py

@@ -129,7 +129,7 @@ def trigger_argument(data: BipolarTriggerRequest):
     if message_id:
         async def trigger_from_message():
             success, error = await force_trigger_argument_from_message_id(
-                channel_id, message_id, globals.client, data.context, topic=data.topic
+                channel_id, message_id, globals.client, data.context
             )
             if not success:
                 logger.error(f"Failed to trigger argument from message: {error}")
@@ -148,8 +148,8 @@ def trigger_argument(data: BipolarTriggerRequest):
     if not channel:
         return JSONResponse(status_code=404, content={"status": "error", "message": f"Channel {channel_id} not found"})
 
-    # Trigger the argument with optional custom topic
-    globals.client.loop.create_task(force_trigger_argument(channel, globals.client, data.context, topic=data.topic))
+    # Trigger the argument — context doubles as the argument theme
+    globals.client.loop.create_task(force_trigger_argument(channel, globals.client, data.context))
 
     return {
         "status": "ok",