fix: 管理会话自动恢复与访问来源统计优化

- 新增 AdminSessionRecover：后台离线/后端重启时自动重试恢复会话，明确失效才回跳登录
- 认证 cookie 契约调整（SameSite=Lax 与刷新轮转适配），路由与守卫适配
- 访问来源统计查询优化与测试、管理端 analytics sources 页面适配
- 移动端布局修正：覆盖 body min-h-screen 避免内容区高度异常

frontend/components/AccountGuard.tsx

@@ -152,7 +152,7 @@ export default function AccountGuard() {
           id="session-ended-dialog-desc"
           className="meta text-[13px] leading-relaxed text-center"
         >
-          你的登录会话已被移除（在安全设置中剔除，或会话数超出上限被淘汰），当前设备的登录状态已失效。
+          你的登录会话已失效（在安全设置中剔除、会话数超出上限被淘汰，或登录有效期已过）。
           请重新登录后继续使用。
         </p>
       </Modal>

frontend/components/Header.tsx

@@ -38,6 +38,11 @@ import { useUrlStyle } from "./SiteBrandProvider";
 import { leaderboardPath } from "@/lib/urlStyle";
 import type { BrandLogoFit, BrandLogoSize, BrandMark } from "@/lib/brand";
 
+// 搜索关键词长度上限（与后端 handler maxSearchKeywordRunes 一致）；
+// 接近上限时输入框内显示 n/100 计数帮助用户感知
+const SEARCH_MAX_LEN = 100;
+const SEARCH_COUNT_FROM = 80;
+
 export default function Header({
   initialUser,
   initialUnread = 0,
@@ -280,18 +285,30 @@ export default function Header({
                 ref={searchInputRef}
                 type="text"
                 value={searchQuery}
+                maxLength={SEARCH_MAX_LEN}
                 onChange={(e) => setSearchQuery(e.target.value)}
                 onKeyDown={onSearchKeyDown}
                 placeholder="搜索帖子..."
                 aria-label="搜索帖子"
-                className="j13-search-field w-full pl-10 pr-10 py-2.5 text-sm rounded-full"
+                className={`j13-search-field w-full pl-10 py-2.5 text-sm rounded-full ${
+                  searchQuery.length >= SEARCH_COUNT_FROM ? "pr-16" : "pr-10"
+                }`}
               />
-              <kbd
-                className="absolute right-3.5 top-1/2 -translate-y-1/2 text-[11px] w-5 h-5 flex items-center justify-center rounded-md pointer-events-none"
-                style={{ color: "var(--ink-3)", border: "1px solid var(--line-2)", background: "var(--bg)" }}
-              >
-                /
-              </kbd>
+              {searchQuery.length >= SEARCH_COUNT_FROM ? (
+                <span
+                  className="absolute right-3.5 top-1/2 -translate-y-1/2 text-[11px] tabular-nums pointer-events-none"
+                  style={{ color: searchQuery.length >= SEARCH_MAX_LEN ? "var(--danger)" : "var(--ink-3)" }}
+                >
+                  {searchQuery.length}/{SEARCH_MAX_LEN}
+                </span>
+              ) : (
+                <kbd
+                  className="absolute right-3.5 top-1/2 -translate-y-1/2 text-[11px] w-5 h-5 flex items-center justify-center rounded-md pointer-events-none"
+                  style={{ color: "var(--ink-3)", border: "1px solid var(--line-2)", background: "var(--bg)" }}
+                >
+                  /
+                </kbd>
+              )}
             </div>
           </form>
           <ThemeToggle initialTheme={initialTheme} className={iconBtn} style={iconBtnStyle} />
@@ -365,6 +382,7 @@ export default function Header({
               autoFocus
               type="text"
               value={searchQuery}
+              maxLength={SEARCH_MAX_LEN}
               onChange={(e) => setSearchQuery(e.target.value)}
               onKeyDown={(e) => {
                 if (e.key === "Escape") {
@@ -374,8 +392,18 @@ export default function Header({
               }}
               aria-label="搜索帖子"
               placeholder="搜索帖子..."
-              className="j13-search-field w-full pl-10 pr-4 py-3 rounded-full text-sm"
+              className={`j13-search-field w-full pl-10 py-3 rounded-full text-sm ${
+                searchQuery.length >= SEARCH_COUNT_FROM ? "pr-16" : "pr-4"
+              }`}
             />
+            {searchQuery.length >= SEARCH_COUNT_FROM && (
+              <span
+                className="absolute right-4 top-1/2 -translate-y-1/2 text-[11px] tabular-nums pointer-events-none"
+                style={{ color: searchQuery.length >= SEARCH_MAX_LEN ? "var(--danger)" : "var(--ink-3)" }}
+              >
+                {searchQuery.length}/{SEARCH_MAX_LEN}
+              </span>
+            )}
           </form>
         </div>
       )}

frontend/components/VisitBeacon.tsx

@@ -1,26 +1,37 @@
 "use client";
 
-import { useEffect, useRef } from "react";
-import { usePathname } from "next/navigation";
+import { Suspense, useEffect, useRef } from "react";
+import { usePathname, useSearchParams } from "next/navigation";
 import { apiTelemetryPageView } from "@/lib/api";
 
-/**
- * 公开站页面访问埋点：同 path 30s 内合并；跳过 /admin。
- */
-export default function VisitBeacon() {
+function BeaconInner() {
   const pathname = usePathname();
+  const search = useSearchParams().toString();
   const lastRef = useRef<{ path: string; at: number }>({ path: "", at: 0 });
 
   useEffect(() => {
     if (!pathname || pathname === "/admin" || pathname.startsWith("/admin/")) return;
+    // 完整 URL（含 query）：query 变化也上报，站内搜索 /?q=… 才能被记录
+    const full = pathname + (search ? `?${search}` : "");
     const now = Date.now();
-    if (lastRef.current.path === pathname && now - lastRef.current.at < 30_000) return;
-    lastRef.current = { path: pathname, at: now };
-    // 带 query 完整路径 + 来源页，供后台来源分析
-    const full = pathname + (typeof window !== "undefined" ? window.location.search : "");
+    if (lastRef.current.path === full && now - lastRef.current.at < 30_000) return;
+    lastRef.current = { path: full, at: now };
+    // 来源页，供后台来源分析
     const ref = typeof document !== "undefined" ? document.referrer : "";
     void apiTelemetryPageView(full, ref);
-  }, [pathname]);
+  }, [pathname, search]);
 
   return null;
 }
+
+/**
+ * 公开站页面访问埋点：同 URL 30s 内合并；跳过 /admin。
+ * useSearchParams 需 Suspense 边界（与 FooterTiming 同模式）。
+ */
+export default function VisitBeacon() {
+  return (
+    <Suspense fallback={null}>
+      <BeaconInner />
+    </Suspense>
+  );
+}