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/leaderboard/leaderboard.wxml

@@ -1,13 +1,15 @@
 <view class="container page-enter" style="{{themeStyle}}">
-  <!-- Period tabs -->
-  <view class="period-tabs">
-    <view
-      wx:for="{{periods}}"
-      wx:key="key"
-      class="period-tab {{activePeriod === item.key ? 'active' : ''}}"
-      data-period="{{item.key}}"
-      bindtap="switchPeriod"
-    >{{item.label}}</view>
+  <!-- Period tabs: pill-style segmented control, consistent with settings -->
+  <view class="period-seg-wrap">
+    <view class="period-seg">
+      <view
+        wx:for="{{periods}}"
+        wx:key="key"
+        class="period-seg-item {{activePeriod === item.key ? 'active' : ''}}"
+        data-period="{{item.key}}"
+        bindtap="switchPeriod"
+      >{{item.label}}</view>
+    </view>
   </view>
 
   <!-- Loading skeleton -->
@@ -27,33 +29,68 @@
     <text class="empty-sub">快去训练吧,争当第一名!</text>
   </view>
 
-  <!-- Rank list -->
-  <view class="rank-list" wx:else>
-    <view
-      wx:for="{{rankedList}}"
-      wx:key="openid"
-      class="rank-item {{item.openid === myEntry.openid ? 'is-me' : ''}} rank-item--enter"
-      style="animation-delay: {{index < 10 ? index * 60 : 0}}ms;"
-    >
-      <view class="rank-num {{item.rank === 1 ? 'gold' : item.rank === 2 ? 'silver' : item.rank === 3 ? 'bronze' : ''}}">
-        <text wx:if="{{item.rank === 1}}">🥇</text>
-        <text wx:elif="{{item.rank === 2}}">🥈</text>
-        <text wx:elif="{{item.rank === 3}}">🥉</text>
-        <text wx:else>{{item.rank}}</text>
+  <block wx:else>
+    <!-- Podium: top 3 (only when there are at least 3 entries) -->
+    <view class="podium" wx:if="{{rankedList.length >= 3}}">
+      <!-- 2nd -->
+      <view class="podium-slot podium-slot--second rank-item--enter" style="animation-delay: 60ms;">
+        <view class="podium-avatar-wrap">
+          <view class="avatar avatar--md {{rankedList[1].avatarUrl ? 'has-avatar' : ''}}"><image class="avatar__img" src="{{rankedList[1].avatarUrl || icons.peopleFill}}" mode="{{rankedList[1].avatarUrl ? 'aspectFill' : 'aspectFit'}}"></image></view>
+          <view class="podium-medal podium-medal--silver">2</view>
+        </view>
+        <text class="podium-name">{{rankedList[1].name}}</text>
+        <text class="podium-dur">{{rankedList[1].durationText}}</text>
+        <view class="podium-base podium-base--second"><text class="podium-base__label">{{rankedList[1].sessions}}次</text></view>
       </view>
-      <image class="rank-avatar" src="{{icons.peopleFill}}" mode="aspectFit"></image>
-      <view class="rank-info">
-        <text class="rank-name">{{item.name}}</text>
-        <text class="rank-sessions">{{item.sessions}}次</text>
+      <!-- 1st -->
+      <view class="podium-slot podium-slot--first rank-item--enter" style="animation-delay: 0ms;">
+        <image class="podium-crown" src="{{icons.crownFill}}" mode="aspectFit"></image>
+        <view class="podium-avatar-wrap">
+          <view class="avatar avatar--md avatar--lg {{rankedList[0].avatarUrl ? 'has-avatar' : ''}}"><image class="avatar__img" src="{{rankedList[0].avatarUrl || icons.peopleFill}}" mode="{{rankedList[0].avatarUrl ? 'aspectFill' : 'aspectFit'}}"></image></view>
+          <view class="podium-medal podium-medal--gold">1</view>
+        </view>
+        <text class="podium-name podium-name--first">{{rankedList[0].name}}</text>
+        <text class="podium-dur podium-dur--first">{{rankedList[0].durationText}}</text>
+        <view class="podium-base podium-base--first"><text class="podium-base__label">{{rankedList[0].sessions}}次</text></view>
+      </view>
+      <!-- 3rd -->
+      <view class="podium-slot podium-slot--third rank-item--enter" style="animation-delay: 120ms;">
+        <view class="podium-avatar-wrap">
+          <view class="avatar avatar--md {{rankedList[2].avatarUrl ? 'has-avatar' : ''}}"><image class="avatar__img" src="{{rankedList[2].avatarUrl || icons.peopleFill}}" mode="{{rankedList[2].avatarUrl ? 'aspectFill' : 'aspectFit'}}"></image></view>
+          <view class="podium-medal podium-medal--bronze">3</view>
+        </view>
+        <text class="podium-name">{{rankedList[2].name}}</text>
+        <text class="podium-dur">{{rankedList[2].durationText}}</text>
+        <view class="podium-base podium-base--third"><text class="podium-base__label">{{rankedList[2].sessions}}次</text></view>
       </view>
-      <text class="rank-dur">{{item.durationText}}</text>
     </view>
-  </view>
+
+    <!-- Rank list: top-3 shown on the podium are skipped when podium exists -->
+    <view class="rank-list">
+      <view
+        wx:for="{{rankedList}}"
+        wx:key="openid"
+        wx:if="{{rankedList.length < 3 || index >= 3}}"
+        class="rank-item {{myEntry && item.openid === myEntry.openid ? 'is-me' : ''}} rank-item--enter"
+        style="animation-delay: {{index < 10 ? index * 60 : 0}}ms;"
+      >
+        <view class="rank-num {{item.rank === 1 ? 'gold' : item.rank === 2 ? 'silver' : item.rank === 3 ? 'bronze' : ''}}">
+          <text>{{item.rank}}</text>
+        </view>
+        <view class="avatar avatar--sm {{item.avatarUrl ? 'has-avatar' : ''}}"><image class="avatar__img" src="{{item.avatarUrl || icons.peopleFill}}" mode="{{item.avatarUrl ? 'aspectFill' : 'aspectFit'}}"></image></view>
+        <view class="rank-info">
+          <text class="rank-name">{{item.name}}</text>
+          <text class="rank-sessions">{{item.sessions}}次</text>
+        </view>
+        <text class="rank-dur">{{item.durationText}}</text>
+      </view>
+    </view>
+  </block>
 
   <!-- My entry pinned at bottom (if not already in list) -->
   <view class="my-bar" wx:if="{{myEntry && myEntry.rank > rankedList.length}}">
-    <view class="rank-num">{{myEntry.rank}}</view>
-    <image class="rank-avatar" src="{{icons.peopleFill}}" mode="aspectFit"></image>
+    <view class="rank-num my-bar__num">{{myEntry.rank}}</view>
+    <view class="avatar avatar--sm my-bar__avatar {{myEntry.avatarUrl ? 'has-avatar' : ''}}"><image class="avatar__img" src="{{myEntry.avatarUrl || icons.peopleFill}}" mode="{{myEntry.avatarUrl ? 'aspectFill' : 'aspectFit'}}"></image></view>
     <view class="rank-info">
       <text class="rank-name">我 ({{myEntry.name}})</text>
       <text class="rank-sessions">{{myEntry.sessions}}次</text>