feat(ui): ReplyPier 品牌、中文界面与前端构建产物

替换品牌文案与图标，补齐窄屏布局和加载失败提示，确认主要旅程可操作。

frontend/src/assets/analytics.svg

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <path d="M3 3V19C3 20.1046 3.89543 21 5 21H21" stroke="currentColor" stroke-width="2" stroke-linecap="round"/>
+  <path d="M7 14L11 10L15 14L21 8" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"/>
+  <circle cx="7" cy="14" r="2" fill="currentColor"/>
+  <circle cx="11" cy="10" r="2" fill="currentColor"/>
+  <circle cx="15" cy="14" r="2" fill="currentColor"/>
+  <circle cx="21" cy="8" r="2" fill="currentColor"/>
+</svg>