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.

frontend/package.json

@@ -18,6 +18,7 @@
   "dependencies": {
     "bootstrap": "^5.3.7",
     "react": "^18.3.1",
+    "react-bootstrap": "^2.10.10",
     "react-dom": "^18.3.1"
   }
 }