fix: Resolve React hooks violation, implement player waiting screen, and auto-start game upon deck submission.

docs/development/devlog/2025-12-14-234500_fix_hooks_and_waiting_state.md

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+# Fix Hooks Violation and Implement Waiting State
+
+## Issue
+1.  **React Hook Error**: Users encountered "Rendered fewer hooks than expected" when the game started. This was caused by conditional returns in `GameRoom.tsx` appearing *before* hook declarations (`useState`, `useEffect`).
+2.  **UX Issue**: Players who submitted their decks remained in the Deck Builder view, able to modify their decks, instead of seeing a waiting screen.
+
+## Fixes
+1.  **Refactored `GameRoom.tsx`**:
+    -   Moved all `useState` and `useEffect` hooks to the top level of the component, ensuring they are always called regardless of the render logic.
+    -   Encapsulated the view switching logic into a helper function `renderContent()`, which is called inside the main return statement.
+2.  **Implemented Waiting Screen**:
+    -   Inside `renderContent`, checking if the room is in `deck_building` status AND if the current player has `ready: true`.
+    -   If ready, displays a "Deck Submitted" screen with a list of other players and their readiness status.
+    -   Updated the sidebar player list to show a "• Ready" indicator.
+
+## Verification
+1.  Start a draft with multiple users (or simulate it).
+2.  Complete draft and enter deck building.
+3.  Submit deck as one player.
+4.  Verify that the view changes to "Deck Submitted" / Waiting screen.
+5.  Submit deck as the final player.
+6.  Verify that the game starts automatically for everyone without crashing (React Error).