fix(vibrate): 修复旧用户震动失效 + 新增震动强度选项

根因:user_settings 早期无 vibrate 字段,getSettings 未兜底,
_remind 的 !s.vibrate 误判 undefined 为关闭,导致震动静默失效,
需手动操作开关才恢复。

- storage: getSettings 兜底 vibrate/voiceGuide/vibrateIntensity 默认值
- timer: !s.vibrate 改 === false,字段缺失视为开(与 voiceGuide 一致)
- timer: vibrate 按 vibrateIntensity 选 API(light/medium=vibrateShort,
  heavy=vibrateLong),fail 回调辅助排查
- settings: 新增"震动强度"三档(短促/标准/强烈),默认强烈

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

pages/settings/settings.wxml

@@ -140,6 +140,21 @@
       </view>
       <switch checked="{{vibrate}}" bindchange="onToggleVibrate" color="{{theme.primary}}"/>
     </view>
+    <view class="setting-row">
+      <view class="setting-left">
+        <image class="setting-icon" src="{{icons.notificationFill}}" mode="aspectFit"></image>
+        <text class="setting-label">震动强度</text>
+      </view>
+      <view class="segmented">
+        <view
+          class="segmented-item {{vibrateIntensity === item.key ? 'active' : ''}}"
+          wx:for="{{vibrateIntensityOptions}}"
+          wx:key="key"
+          data-key="{{item.key}}"
+          bindtap="onSelectVibrateIntensity"
+        >{{item.name}}</view>
+      </view>
+    </view>
   </ui-card>
 
   <!-- 数据管理 -->