fix: keep manual favorites when no nav visit data; external-only visits don't trigger reorder

- Favorites section only rebuilds from Top-4 by visit frequency once real
  navigation hosts have visit data; otherwise manual Gitea/HomeAgent/AgentMail
  items are preserved untouched
- Pure external-site history (wikipedia etc.) no longer causes favorites to
  borrow tiles from other sections

history-server/main.go

@@ -301,6 +301,7 @@ func rebuildDashySections() {
 
     // 收集所有导航项（排除历史访问 section 本身），带 host 访问量
     hv := hostVisits()
+
     type cand struct {
         nav    dashyNav
         host   string
@@ -346,6 +347,36 @@ func rebuildDashySections() {
         return candidates[i].visits > candidates[j].visits
     })
 
+    // 导航项若均无访问记录（首次/纯外站访问），保持常用服务原手动配置不动
+    {
+        anyNav := false
+        for _, c := range candidates {
+            if c.visits > 0 {
+                anyNav = true
+                break
+            }
+        }
+        if !anyNav {
+            for _, si := range secs {
+                if si.name == histName {
+                    si.raw["items"] = []any{map[string]any{
+                        "title": "\u7b49\u5f85\u6d4f\u89c8\u5668\u63d2\u4ef6\u63a5\u5165...",
+                        "description": "\u540c\u6b65\u540e\u6309\u603b\u8bbf\u95ee\u9891\u6b21\u81ea\u52a8\u6392\u5e8f",
+                        "icon": "fas fa-info-circle", "url": "/admin/",
+                    }}
+                }
+            }
+            out, err := yaml.Marshal(cfg)
+            if err == nil {
+                tmp := confFile + ".sort-tmp"
+                if err2 := os.WriteFile(tmp, out, 0644); err2 == nil {
+                    os.Rename(tmp, confFile)
+                }
+            }
+            return
+        }
+    }
+
     // host 去重：同 host 只保留访问最高的一条导航项
     // （rebuild 前常用服务可能已有上一轮写入的副本，与其它 section 同 host 会重复）
     {