fix(HEL-243): 当前账号可点击返回，避免切换死路

当前账号行原先只显示对号、不可点击，单账号时只能关网页。现改为整行继续使用且不重新签发会话，并带回切换前的业务页。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

frontend/login/page.js

@@ -77,9 +77,22 @@
     return chips.join("");
   }
 
+  function returnPath() {
+    const raw = new URLSearchParams(global.location.search).get("next") || "";
+    if (!raw) return "/";
+    try {
+      const url = new URL(raw, global.location.origin);
+      if (url.origin !== global.location.origin) return "/";
+      const path = url.pathname || "/";
+      if (path === "/login" || path.startsWith("/login/")) return "/";
+      return `${path}${url.search}${url.hash}` || "/";
+    } catch (_error) {
+      return "/";
+    }
+  }
+
   function enterApp() {
-    const next = new URLSearchParams(global.location.search).get("next");
-    global.location.replace(next && next.startsWith("/") ? next : "/");
+    global.location.replace(returnPath());
   }
 
   function formMarkup(options) {
@@ -120,7 +133,7 @@
       "login-account-row",
       current ? "is-current" : "",
       confirming ? "is-confirming" : "",
-      !managing && !current ? "is-switchable" : "",
+      !managing ? "is-switchable" : "",
     ].filter(Boolean).join(" ");
     if (managing && confirming) {
       return [
@@ -138,11 +151,12 @@
     const action = managing
       ? `<button class="login-account-remove" type="button" data-confirm-id="${account.user_id}" aria-label="移除 ${escapeHtml(account.username)}"><svg width="16" height="16" viewBox="0 0 16 16" aria-hidden="true"><path fill="currentColor" d="M6 2h4l.5 1H14v1H2V3h3.5L6 2zm1 4v6H6V6h1zm3 0v6H9V6h1zM3.5 5H13l-.7 8.2A1.5 1.5 0 0 1 10.81 14H5.19a1.5 1.5 0 0 1-1.49-1.8L3.5 5z"></path></svg></button>`
       : current
-        ? '<span class="login-account-check" aria-hidden="true">✓</span>'
+        ? '<span class="login-account-action"><span class="login-account-check" aria-hidden="true">✓</span>继续使用</span>'
         : "";
     const switchAttr = !managing && !current ? ` data-switch-id="${account.user_id}"` : "";
+    const resumeAttr = !managing && current ? ` data-resume-id="${account.user_id}"` : "";
     return [
-      `<div class="${classes}" data-user-id="${account.user_id}"${switchAttr}>`,
+      `<div class="${classes}" data-user-id="${account.user_id}"${switchAttr}${resumeAttr}>`,
       `<span class="login-avatar tone-${tone}" aria-hidden="true">${glyph}</span>`,
       '<div class="login-account-meta">',
       '<div class="login-account-name">',
@@ -160,6 +174,9 @@
     const count = state.accounts.length;
     const managing = state.view === "manage";
     return [
+      managing
+        ? ""
+        : '<button class="login-back" type="button" data-login-action="resume">返回复盘</button>',
       `<h2 class="login-card-title">${managing ? "管理账号记录" : "选择账号"}</h2>`,
       `<p class="login-card-lead">${managing
         ? "移除只删除这台电脑上的登录记录，不会注销账号"
@@ -210,6 +227,10 @@
     card.querySelectorAll("[data-login-action]").forEach((button) => {
       button.addEventListener("click", () => {
         const action = button.dataset.loginAction;
+        if (action === "resume") {
+          resumeCurrentAccount();
+          return;
+        }
         if (action === "picker") {
           state.view = state.accounts.length ? "picker" : "first";
           state.confirmingId = null;
@@ -228,6 +249,9 @@
     card.querySelectorAll("[data-switch-id]").forEach((button) => {
       button.addEventListener("click", () => switchAccount(Number(button.dataset.switchId)));
     });
+    card.querySelectorAll("[data-resume-id]").forEach((button) => {
+      button.addEventListener("click", () => resumeCurrentAccount());
+    });
     card.querySelectorAll("[data-confirm-id]").forEach((button) => {
       button.addEventListener("click", (event) => {
         event.stopPropagation();
@@ -291,6 +315,27 @@
     }
   }
 
+  async function resumeCurrentAccount() {
+    state.loading = true;
+    setError("");
+    render();
+    try {
+      const session = await api.request("/api/auth/me");
+      const sessionUserId = session.user?.id;
+      const matches = Boolean(session.authenticated) && (
+        !state.currentUserId || Number(sessionUserId) === Number(state.currentUserId)
+      );
+      if (!matches) {
+        throw new Error("当前会话已失效，请重新登录");
+      }
+      enterApp();
+    } catch (error) {
+      state.loading = false;
+      setError(error.message || "当前会话已失效，请重新登录");
+      render();
+    }
+  }
+
   async function forgetAccount(userId) {
     try {
       await api.request("/api/auth/forget", "POST", { user_id: userId });