chore: 上线前优化 — 清理调试日志/启用组件按需注入/补全组件声明

- 移除全项目 34 处调试 console.* 输出
- project.config.json: minified true、uploadWithSourceMap false、启用 lazyCodeLoading(requiredComponents 组件按需注入)
- pages/records/records.json 补全 ui-skeleton 组件声明(此前漏声明,WXML 已使用)
- 删除根目录残留 preview-buttons.html

pages/records/records.json

@@ -2,7 +2,8 @@
   "usingComponents": {
     "calendar-heatmap": "/components/calendar-heatmap/calendar-heatmap",
     "trend-chart": "/components/trend-chart/trend-chart",
-    "ui-card": "/components/ui-card/ui-card"
+    "ui-card": "/components/ui-card/ui-card",
+    "ui-skeleton": "/components/ui-skeleton/ui-skeleton"
   },
   "navigationBarTitleText": "训练记录"
 }