feat(ui): 记录页月份联动与多项 UI 美化/修复

- records: 底部列表与月份选择器联动，新增 [本月|最近] 分段控件；标题/空态随模式切换
- leaderboard: 领奖台布局(冠军居中+皇冠)、次数标注于底座且三档水平对齐；头像 cloud:// 批量预解析提速(云函数需重新部署)
- index/timer: 主色底图标改白色变体修复隐形；目标数字按微信字体缩放补偿真机遮挡
- settings: 配色方案横滑渐变色卡；头像上传前压缩至 200px
- theme: 新增 teal 主题；暗黑背景统一对齐
- 圆形头像双保险(image 自身 border-radius)修复月/年榜方图

注: cloudfunctions/leaderboard 改动须在开发者工具重新部署才生效。

pages/index/index.wxss

@@ -54,8 +54,11 @@
 .streak-num {
   font-size: 56rpx;
   font-weight: 700;
-  color: var(--primary);
-  line-height: 1.1;
+  /* On the gradient hero card --text cascades to white; on any plain card it
+     stays dark, so var(--text) reads correctly in both contexts. We must NOT
+     use var(--primary) here — that would be orange-on-orange and invisible. */
+  color: var(--text);
+  text-shadow: 0 2rpx 8rpx rgba(0, 0, 0, 0.12);
 }
 
 .streak-label {
@@ -114,7 +117,9 @@
 
 .progress-fill {
   height: 100%;
-  background: linear-gradient(90deg, var(--primary), var(--primary-light));
+  /* On the gradient hero card --on-primary (white) overrides the fallback,
+     so the fill stays visible instead of blending into the orange card. */
+  background: var(--on-primary, linear-gradient(90deg, var(--primary), var(--primary-light)));
   border-radius: 4rpx;
   transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
   position: relative;
@@ -126,9 +131,9 @@
   top: -4rpx;
   width: 16rpx;
   height: 16rpx;
-  background: var(--primary);
+  background: var(--on-primary, var(--primary));
   border-radius: 50%;
-  box-shadow: 0 0 10rpx var(--primary);
+  box-shadow: 0 0 10rpx var(--on-primary, var(--primary));
 }
 
 .progress-label {
@@ -167,20 +172,27 @@
   display: inline-flex;
   align-items: center;
   justify-content: center;
-  width: 200rpx;
-  height: 200rpx;
+  width: 280rpx;
+  height: 280rpx;
   border-radius: 50%;
-  background: linear-gradient(135deg, rgba(var(--primary-rgb), 0.08), rgba(var(--primary-rgb), 0.02));
-  border: 4rpx solid rgba(var(--primary-rgb), 0.15);
-  margin-bottom: 16rpx;
+  background: linear-gradient(135deg, rgba(var(--primary-rgb), 0.10), rgba(var(--primary-rgb), 0.03));
+  border: 6rpx solid rgba(var(--primary-rgb), 0.18);
+  box-shadow: 0 0 0 14rpx rgba(var(--primary-rgb), 0.05);
+  margin-bottom: 20rpx;
+  overflow: hidden;
 }
 
 .target-time {
-  font-size: 64rpx;
-  font-weight: 700;
+  font-size: 84rpx;
+  font-weight: 800;
   color: var(--primary);
   font-variant-numeric: tabular-nums;
+  letter-spacing: -1rpx;
   line-height: 1;
+  max-width: 240rpx;
+  text-align: center;
+  white-space: nowrap;
+  overflow: hidden;
 }
 
 .target-unit {