fix: 修复头像存储、日历详情数据与弹窗定位问题

- settings: 补上缺失的 util 导入,onChooseAvatar 不再抛
  ReferenceError,头像走 data URI 永久存储主路径
- records: 日历详情改用 dateOnly 比较,修复详情永远显示 0 次/0 时长
- records: 日历详情弹窗从 ui-modal 改为普通 view + fixed,
  修复被底部 dock 遮挡/不居中;补暗黑阴影描边与滚动穿透处理

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pages/records/records.json

@@ -1,8 +1,7 @@
 {
   "usingComponents": {
     "calendar-heatmap": "/components/calendar-heatmap/calendar-heatmap",
-    "ui-card": "/components/ui-card/ui-card",
-    "ui-modal": "/components/ui-modal/ui-modal"
+    "ui-card": "/components/ui-card/ui-card"
   },
   "navigationBarTitleText": "训练记录"
 }