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/styles.css

@@ -68,8 +68,7 @@ input,select,textarea{font-family:var(--font);color:var(--text)}
 .top-search{background:var(--card);border:1px solid var(--border);border-radius:6px;color:var(--text-2);padding:5px 12px;font-size:13px;width:230px}
 .theme-btn{border:1px solid var(--border);background:var(--card);color:var(--text-2);border-radius:6px;padding:5px 11px;font-size:12.5px;cursor:pointer;white-space:nowrap}
 .theme-btn:hover{border-color:var(--primary);color:var(--primary-text)}
-.avatar{width:30px;height:30px;border-radius:50%;background:linear-gradient(135deg,#1668dc,#13c2c2);display:inline-flex;align-items:center;justify-content:center;font-size:12px;color:#fff;font-weight:600;flex:none}
-.content{padding:16px 20px 28px;max-width:1460px;width:100%;margin:0 auto}
+.content{padding:24px;width:100%}
 .panel{background:var(--card);border:1px solid var(--border-soft);border-radius:var(--radius);margin-bottom:16px}
 .panel-head{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:10px 16px;border-bottom:1px solid var(--border-soft)}
 .panel-head h2{font-size:14.5px;font-weight:600}
@@ -181,6 +180,10 @@ tbody tr.drag-over td{border-top:2px solid var(--primary)}
 .icon-btn:hover{color:var(--primary-text);background:var(--hover-bg)}
 .icon-btn.del{color:var(--red-text)}
 .icon-btn.del:hover{background:var(--red-soft);color:var(--red-text)}
+/* 图标悬停提示气泡（3x-ui 式：黑底白字圆角 + 小尖角，挂 body 避免被表格滚动容器裁剪） */
+.tip-bubble{position:fixed;z-index:200;pointer-events:none;background:#141414;color:#fff;font-size:12px;line-height:1.25;padding:6px 9px;border-radius:6px;white-space:nowrap;opacity:0;transition:opacity .12s;box-shadow:0 4px 14px rgba(0,0,0,.25)}
+.tip-bubble.show{opacity:1}
+.tip-bubble::after{content:"";position:absolute;top:100%;left:var(--tip-arrow-left,50%);transform:translateX(-50%);border:5px solid transparent;border-top-color:#141414;border-bottom:0}
 .tgl{position:relative;display:inline-block;width:38px;height:21px;vertical-align:middle;flex:none}
 .tgl input{opacity:0;width:0;height:0;position:absolute}
 .tgl .tr{position:absolute;inset:0;background:var(--tgl-off);border-radius:99px;transition:background .2s;cursor:pointer}
@@ -206,7 +209,7 @@ tbody tr.drag-over td{border-top:2px solid var(--primary)}
 .empty b{display:block;color:var(--text-2);font-size:14px;margin-bottom:2px}
 
 /* ---------- 服务器页 ---------- */
-.stats{display:grid;grid-template-columns:repeat(4,1fr);background:var(--card);border:1px solid var(--border-soft);border-radius:var(--radius);margin-bottom:14px}
+.stats{display:grid;grid-template-columns:repeat(3,1fr);background:var(--card);border:1px solid var(--border-soft);border-radius:var(--radius);margin-bottom:14px}
 .stats .stat{padding:14px 22px;border:none;background:transparent}
 .stats .stat .lab{color:var(--text-2);font-size:12.5px;margin-bottom:3px}
 .stats .stat .val{display:flex;align-items:center;gap:8px;font-size:20px;font-weight:600;font-variant-numeric:tabular-nums}
@@ -399,4 +402,4 @@ label>input:focus,label>select:focus,label>textarea:focus{border-color:var(--pri
 .toast.error{border-left-color:var(--red)}
 
 @media (max-width:1100px){.stat-grid{grid-template-columns:repeat(2,1fr)}.mid-grid{grid-template-columns:1fr}.info-bar{flex-direction:column;gap:14px}.info-bar .seg{padding:0}.info-bar .seg+.seg{border-left:none}.stats{grid-template-columns:repeat(2,1fr)}}
-@media (max-width:760px){.sider{display:none}.form-grid{grid-template-columns:1fr}.top-search{display:none}}
+@media (max-width:760px){.sider{display:none}.form-grid{grid-template-columns:1fr}.top-search{display:none}.content{padding:8px}}