feat(web): UI batch — content width, latency removal, icon tooltips, avatar removal (round-2 #3/#5/#6/#9)

#3 .content: drop max-width:1460px centering, padding 24px full width
   (3x-ui content-area parity), 8px under the 760px breakpoint.
#5 servers page: remove latency column + average-latency stat cell
   (stats grid 4->3, table 15->14 cols incl. detail colspan/empty row).
#6 icon buttons: native title replaced by data-tip with a 3x-ui style
   bubble (black/white, rounded, arrow, body-level fixed layer so table
   scroll containers cannot clip it); customer QR tip renamed to 二维码;
   covers customers/servers/nodes rows, credentials pane, links pane,
   address eye toggle, drag grip, filter chip clear, logout, modal close.
#9 remove decorative topbar avatar span#avatar, its showApp assignment
   and the dead .avatar CSS rule. Refresh button untouched.

Golden re-captured: sole diff was errors.badSubscription body (the SPA
index.html served there) reflecting the avatar/data-tip changes.

public/index.html

@@ -34,7 +34,7 @@
         <a class="mi" data-page="commands" href="#commands"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M4 17l6-5-6-5M12 19h8"/></svg>安装与命令</a>
         <a class="mi" data-page="operations" href="#operations"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><circle cx="12" cy="12" r="3"/><path d="M19 12a7 7 0 00-.1-1.2l2-1.5-2-3.4-2.3 1a7 7 0 00-2-1.2L14.2 3h-4l-.4 2.5a7 7 0 00-2 1.2l-2.3-1-2 3.4 2 1.5A7 7 0 005 12c0 .4 0 .8.1 1.2l-2 1.5 2 3.4 2.3-1a7 7 0 002 1.2l.4 2.7h4l.4-2.5a7 7 0 002-1.2l2.3 1 2-3.4-2-1.5c.1-.4.1-.8.1-1.2z"/></svg>设置与运维</a>
       </nav>
-      <div class="sider-foot"><span id="user-chip"></span><span class="foot-right"><span id="version-label"></span><button id="logout" class="icon-btn" type="button" title="退出登录"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8"><path d="M9 21H5a2 2 0 01-2-2V5a2 2 0 012-2h4"/><path d="M16 17l5-5-5-5M21 12H9"/></svg></button></span></div>
+      <div class="sider-foot"><span id="user-chip"></span><span class="foot-right"><span id="version-label"></span><button id="logout" class="icon-btn" type="button" data-tip="退出登录"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8"><path d="M9 21H5a2 2 0 01-2-2V5a2 2 0 012-2h4"/><path d="M16 17l5-5-5-5M21 12H9"/></svg></button></span></div>
     </aside>
 
     <div class="main">
@@ -44,7 +44,6 @@
         <input class="top-search" placeholder="搜索服务器、客户、节点…" disabled>
         <button class="theme-btn" id="refresh" type="button" title="刷新数据">刷新</button>
         <button class="theme-btn" type="button" data-theme-toggle>🌙 深色</button>
-        <span class="avatar" id="avatar">管</span>
       </header>
       <main class="content" id="content"></main>
     </div>
@@ -52,7 +51,7 @@
 
   <div id="modal-overlay" class="modal-overlay hidden">
     <section class="modal panel" role="dialog" aria-modal="true">
-      <header class="modal-head"><h2 id="modal-title"></h2><button type="button" class="icon-btn" data-close aria-label="关闭"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8"><path d="M18 6L6 18M6 6l12 12"/></svg></button></header>
+      <header class="modal-head"><h2 id="modal-title"></h2><button type="button" class="icon-btn" data-close aria-label="关闭" data-tip="关闭"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8"><path d="M18 6L6 18M6 6l12 12"/></svg></button></header>
       <div id="modal-body" class="modal-body"></div>
     </section>
   </div>