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/models.py

@@ -45,8 +45,7 @@ class LogFilterUpdateRequest(BaseModel):
 class BipolarTriggerRequest(BaseModel):
     channel_id: str  # String to handle large Discord IDs from JS
     message_id: str = None  # Optional: starting message ID (string)
-    context: str = ""
-    topic: str = ""  # Optional: custom argument topic (overrides random topic selection)
+    context: str = ""  # Optional: argument theme/context — tells them what to argue about
 
 
 class ManualCropRequest(BaseModel):