fix: 修复赛事规程下载文件无后缀问题

- event-rules页面H5环境使用a标签download属性指定文件名
- 修复api.config.js生产环境API地址配置
- 优化多个页面的附件展示

🤖 Generated with Claude Code

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

src/pages/event-register/event-register.vue

@@ -485,9 +485,9 @@ export default {
         // 构建提交数据 - 确保ID都是数字类型
         const submitData = {
           orderNo: orderNo,
-          competitionId: parseInt(this.eventId),
-          projectIds: this.selectedProjects.map(p => parseInt(p.id)),
-          athleteIds: selected.map(p => parseInt(p.id)),
+          competitionId: String(this.eventId),
+          projectIds: this.selectedProjects.map(p => String(p.id)),
+          athleteIds: selected.map(p => String(p.id)),
           contactPhone: this.eventInfo.contact || '',
           totalAmount: parseFloat(this.totalPrice) || 0
         }