feat: 添加货币格式化配置，支持自定义小数位和分隔符，增强 API 响应的可读性

config/lottery.php

@@ -79,4 +79,17 @@ return [
         /** 结果发布后的冷静期（分钟），{@see draws.cooling_end_time} */
         'cooldown_minutes' => max(0, (int) env('LOTTERY_DRAW_COOLDOWN_MINUTES', 15)),
     ],
+
+    /*
+    | ui.format：API 中 *_formatted 展示用（由 {@see \App\Support\CurrencyFormatter} 读取）
+    */
+    'ui' => [
+        'format' => [
+            'currency' => [
+                'decimals' => max(0, min(12, (int) env('LOTTERY_CURRENCY_DISPLAY_DECIMALS', 2))),
+                'decimal_separator' => env('LOTTERY_CURRENCY_DECIMAL_SEP', '.'),
+                'thousands_separator' => env('LOTTERY_CURRENCY_THOUSANDS_SEP', ','),
+            ],
+        ],
+    ],
 ];