用户消息系统：消息列表、订单群聊、联系对方入口

- 新增消息列表页和聊天详情页，支持 SSE 实时推送
- 订单详情页新增"联系对方"按钮，一键进入订单群聊
- 导航栏新增"消息"入口
- 修复 mobileHost 路径匹配 bug，避免 /m 前缀误匹配
- 优化 dev.sh：提取 mysql 辅助函数、修复空 PID 处理、条件检查依赖

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/router/mobileHost.ts

@@ -14,7 +14,7 @@ export function getMobilePath(path: string): string {
   if (path === "/" || path === "") {
     return "/m";
   }
-  if (path.startsWith("/m") || path.startsWith("/admin")) {
+  if (path === "/m" || path.startsWith("/m/") || path.startsWith("/admin")) {
     return path;
   }
   
@@ -31,6 +31,9 @@ export function getMobilePath(path: string): string {
   if (path === "/seller/listings/create") {
     return "/m/seller/listings/create";
   }
+  if (path === "/messages" || path.startsWith("/messages/")) {
+    return "/m/messages";
+  }
   
   // PC-only views that don't have mobile counterparts go to mobile profile as fallback
   if (path === "/wallet" || path === "/notifications" || path.startsWith("/seller")) {
@@ -41,7 +44,7 @@ export function getMobilePath(path: string): string {
 }
 
 export function getPcPath(path: string): string {
-  if (!path.startsWith("/m") || path.startsWith("/admin")) {
+  if ((path !== "/m" && !path.startsWith("/m/")) || path.startsWith("/admin")) {
     return path;
   }
   
@@ -62,7 +65,8 @@ export function getPcPath(path: string): string {
   if (subPath === "/realname") return "/realname";
   if (subPath === "/seller/listings/create") return "/seller/listings/create";
   
-  if (subPath === "/messages") return "/";
+  if (subPath === "/messages") return "/messages";
+  if (subPath.startsWith("/chats/")) return "/messages/" + subPath.substring(7);
   if (subPath === "/profile") return "/wallet";
   
   return subPath || "/";