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.wxss

@@ -221,7 +221,57 @@
   line-height: 1;
 }
 
-/* ---- day detail popup ---- */
+/* ---- day detail popup ----
+   普通 view 实现,不用 ui-modal:自定义组件根元素的 position: fixed
+   会被小程序运行时吞掉(见 settings.wxss plan-editor 注释),叠加
+   .page-enter 的 transform 会让 fixed 降级相对 .container,导致弹窗
+   落到容器末尾而非视口居中。普通 view 的 fixed 100% 生效。 */
+.day-detail-mask {
+  position: fixed;
+  top: 0; left: 0; right: 0; bottom: 0;
+  z-index: 1000;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.day-detail-mask__bg {
+  position: absolute;
+  top: 0; left: 0; right: 0; bottom: 0;
+  background: rgba(0, 0, 0, 0.45);
+  animation: dayDetailFade 0.25s ease;
+}
+
+.day-detail-body {
+  position: relative;
+  width: 560rpx;
+  border-radius: 28rpx;
+  padding: 48rpx 40rpx 36rpx;
+  background: var(--card-bg);
+  box-sizing: border-box;
+  text-align: center;
+  box-shadow: 0 16rpx 48rpx rgba(0, 0, 0, 0.25);
+  animation: dayDetailPop 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
+}
+
+@media (prefers-color-scheme: dark) {
+  .day-detail-body {
+    /* 暗黑下 body(#1C1C1E)与页面(#0F0F12)都偏深,加深阴影 + 微亮描边拉开层次 */
+    box-shadow: 0 16rpx 48rpx rgba(0, 0, 0, 0.6), 0 0 0 1rpx rgba(255, 255, 255, 0.06);
+  }
+}
+
+@keyframes dayDetailFade {
+  from { opacity: 0; }
+  to   { opacity: 1; }
+}
+
+@keyframes dayDetailPop {
+  from { transform: scale(0); opacity: 0; }
+  60%  { transform: scale(1.05); }
+  to   { transform: scale(1); opacity: 1; }
+}
+
 .detail-date-row {
   display: flex;
   align-items: center;