Add live bidding UI and backend support; integrate react-bootstrap

- Added 'react-bootstrap' to frontend dependencies for improved UI components.
- Updated bid placement mechanics: backend now stores bids as a list of {user, amount}; frontend displays live bid leaderboard, including highest bid.
- Implemented bid placement form and UI in participant draft screen.
- Used React-Bootstrap Collapse for nominee menu accordion behavior.
- Expanded DraftStateManager and websocket consumers to broadcast bid updates in the new format.
- Added missing 'bids' syncing to all relevant state handling code.
- Improved styling for bidding, panel headers, and pick lists in SCSS; leveraged Bootstrap variables/utilities more extensively.
- Other minor JS, Python, and style tweaks for better stability and robustness.

draft/constants.py

@@ -32,6 +32,7 @@ class DraftMessage(StrEnum):
     BID_START_INFORM         = "bid.start.inform"             # server -> client (movie, ends_at)
     BID_START_REQUEST        = "bid.start.request"             # server -> client (movie, ends_at)
     BID_PLACE_REQUEST        = "bid.place.request"            # client -> server (amount)
+    BID_PLACE_CONFIRM        = "bid.update.confirm"            # server -> client (high bid)
     BID_UPDATE_INFORM        = "bid.update.inform"            # server -> client (high bid)
     BID_END_INFORM           = "bid.end.inform"               # server -> client (winner)