feat: refactor lobby UI with collapsible panels, add player event notifications, and update card art crop threshold to 130px

docs/development/devlog/2025-12-18-023000_lobby_ui_update.md

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+# Work Plan - Lobby & Chat UI Overhaul and Notifications
+
+## Request
+1.  **Lobby/Chat Sidebar**: Refactor to be collapsible on the right edge.
+    - Add floating/modal panel for Lobby and Chat content.
+    - Remove fixed right column layout.
+2.  **Notifications**: Implement toast notifications for player events (Join, Leave, Disconnect).
+    - Add setting to Enable/Disable notifications (persisted).
+3.  **Deck Builder**: Update "Full Card" display trigger to new slider range (50% = 130px).
+
+## Changes
+- **DeckBuilderView.tsx**:
+    - Updated `useArtCrop` logic: `cardWidth < 130` (was 200).
+
+- **GameRoom.tsx**:
+    - Refactored layout: Added `activePanel` state.
+    - Created `useEffect` hook with `prevPlayersRef` to detect changes and trigger toasts.
+    - Added "Notifications On/Off" toggle in Lobby panel.
+    - Implemented floating side panel UI for desktop.
+    - Updated mobile view (kept separate mobile tab logic but ensured layout stability).
+
+- **Toast.tsx**:
+    - Added `'warning'` type support for amber-colored alerts (Player Left).
+
+## Verification
+- Verified `ref` based diffing logic for notifications.
+- Verified persistence of notification settings in `localStorage`.
+- checked `Toast` type definition update.