feat: festive Chinese red background and prize config unification

- Change all big screen backgrounds to pure Chinese red (#c41230)
- Remove vignette effect for consistent display on different screens
- Unify all prize data to match prizes.json configuration
- Add demo participants fallback when no data imported
- Fix particle visibility reset in startGalaxy()

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/server/src/services/admin.service.ts

@@ -419,9 +419,9 @@ class AdminService {
           this.state.lottery = {
             round: 1,
             subPhase: 'IDLE',
-            prizeLevel: firstPrize?.level || '特等奖',
-            prizeName: firstPrize?.name || '待配置',
-            winnerCount: firstPrize?.winnerCount || 1,
+            prizeLevel: firstPrize?.level || '第一轮抽奖',
+            prizeName: firstPrize?.name || '幸运伴手礼',
+            winnerCount: firstPrize?.winnerCount || 7,
             currentWinners: [],
           };
           break;
@@ -497,12 +497,15 @@ class AdminService {
       }
 
       if (scope === 'all' || scope === 'lottery') {
+        // 从配置获取第一轮奖项
+        const prizes = prizeConfigService.getPrizes();
+        const firstPrize = prizes.find(p => p.round === 1) || prizes[0];
         this.state.lottery = {
           round: 1,
           subPhase: 'IDLE',
-          prizeLevel: '特等奖',
-          prizeName: 'iPhone 16 Pro Max',
-          winnerCount: 1,
+          prizeLevel: firstPrize?.level || '第一轮抽奖',
+          prizeName: firstPrize?.name || '幸运伴手礼',
+          winnerCount: firstPrize?.winnerCount || 7,
           currentWinners: [],
         };
       }

packages/server/src/services/prize-config.service.ts

@@ -61,10 +61,10 @@ class PrizeConfigService {
     private getDefaults(): PrizeConfigFile {
         return {
             prizes: [
-                { round: 1 as LotteryRound, level: '特等奖', name: 'iPhone 16 Pro Max', winnerCount: 1 },
-                { round: 2 as LotteryRound, level: '一等奖', name: 'iPad Pro', winnerCount: 3 },
-                { round: 3 as LotteryRound, level: '二等奖', name: 'AirPods Pro', winnerCount: 5 },
-                { round: 4 as LotteryRound, level: '三等奖', name: '京东卡 500元', winnerCount: 10, zodiacFilter: 'horse' },
+                { round: 1 as LotteryRound, level: '第一轮抽奖', name: '幸运伴手礼', winnerCount: 7 },
+                { round: 2 as LotteryRound, level: '第二轮抽奖', name: '幸运伴手礼', winnerCount: 3 },
+                { round: 3 as LotteryRound, level: '第三轮抽奖', name: '幸运伴手礼', winnerCount: 4 },
+                { round: 4 as LotteryRound, level: '第四轮抽奖', name: '幸运伴手礼', winnerCount: 1, zodiacFilter: 'horse' },
             ],
             settings: {
                 minStormDuration: 3000,