fix: format hour display on Loop End screen to avoid floating-point precision errors

- Use formatHour() instead of raw {hour} to display time in HH:MM format
  (e.g. '15:00' instead of '14.999999999999998')
- Export formatHour from stores barrel index
- Fixes #336

src/app/components/GameOverScreen.tsx

@@ -2,7 +2,7 @@
 
 import { Button } from '@/components/ui/button';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
-import { fmt } from '@/lib/game/stores';
+import { fmt, formatHour } from '@/lib/game/stores';
 import { useGameStore } from '@/lib/game/stores';
 
 interface GameOverScreenProps {
@@ -40,7 +40,7 @@ export function GameOverScreen({ day, hour, insightGained, totalInsight }: GameO
               <div className="text-xs text-gray-400">Day Reached</div>
             </div>
             <div className="p-3 bg-gray-800 rounded">
-              <div className="text-xl font-bold text-purple-400 game-mono">{hour}</div>
+              <div className="text-xl font-bold text-purple-400 game-mono">{formatHour(hour)}</div>
               <div className="text-xs text-gray-400">Hour</div>
             </div>
             <div className="p-3 bg-gray-800 rounded">

src/lib/game/stores/index.ts

@@ -32,6 +32,7 @@ export type { GameCoordinatorStore } from './gameStore';
 export {
   fmt,
   fmtDec,
+  formatHour,
   getFloorMaxHP,
   getFloorElement,
   getFloorElements,