Add disable timer setting and fix per-question time limits

Add a 'Question Timer' toggle to game settings that lets the host disable
the countdown timer. When disabled, questions show ∞ instead of a countdown,
the host gets an 'End Question' button to manually advance, and all correct
answers receive maximum points.

Also fix a bug where per-question time limits were ignored — the timer and
scoring always used the hardcoded 20-second default instead of each question's
individual timeLimit.

tests/components/DefaultConfigModal.test.tsx

@@ -294,6 +294,8 @@ describe('DefaultConfigModal', () => {
         penaltyPercent: 30,
         firstCorrectBonusEnabled: true,
         firstCorrectBonusPoints: 75,
+        timerEnabled: true,
+        maxPlayers: 10,
       };
       
       render(<DefaultConfigModal {...defaultProps} config={allEnabledConfig} />);

tests/components/GameConfigPanel.test.tsx

@@ -415,6 +415,8 @@ describe('GameConfigPanel', () => {
         penaltyPercent: 30,
         firstCorrectBonusEnabled: true,
         firstCorrectBonusPoints: 75,
+        timerEnabled: true,
+        maxPlayers: 10,
       };
       
       render(<GameConfigPanel {...defaultProps} config={allEnabledConfig} />);
@@ -439,6 +441,8 @@ describe('GameConfigPanel', () => {
         penaltyPercent: 25,
         firstCorrectBonusEnabled: false,
         firstCorrectBonusPoints: 50,
+        timerEnabled: true,
+        maxPlayers: 10,
       };
       
       render(<GameConfigPanel {...defaultProps} config={allDisabledConfig} />);

tests/components/QuizEditorConfig.test.tsx

@@ -347,6 +347,8 @@ describe('QuizEditor - Game Config Integration', () => {
           penaltyPercent: 30,
           firstCorrectBonusEnabled: true,
           firstCorrectBonusPoints: 75,
+          timerEnabled: true,
+          maxPlayers: 10,
         },
       });