feat: 站点访问统计与可配置侧边栏组件

- 新增访问统计：visitstats 服务与查询、visit_capture 中间件、爬虫/来源识别、管理端 analytics 页面
- 新增侧边栏：sidebar 服务与 handler、管理端 sidebar 配置页、前端侧边栏组件
- 新增 widget 嵌入代码生成（widgetCode）与 widgetApi
- 遥测逻辑迁移至 handler 层，删除 service/telemetry
- env 示例补充 Docker 部署可信代理 IP 说明

backend/service/visit_bot_test.go

@@ -0,0 +1,31 @@
+package service
+
+import "testing"
+
+func TestClassifyBot(t *testing.T) {
+	cases := []struct {
+		ua   string
+		want string
+	}{
+		{"Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)", "Googlebot"},
+		{"Mozilla/5.0 (compatible; bingbot/2.0)", "bingbot"},
+		{"Mozilla/5.0 (compatible; Baiduspider/2.0)", "Baiduspider"},
+		{"Mozilla/5.0 (compatible; Bytespider; https://zhanzhang.toutiao.com/)", "Bytespider"},
+		{"curl/8.4.0", "curl"},
+		{"Wget/1.21", "Wget"},
+		{"python-requests/2.31", "python-requests"},
+		{"Go-http-client/2.0", "Go-http-client"},
+		{"GPTBot/1.0", "GPTBot"},
+		{"ClaudeBot/1.0", "ClaudeBot"},
+		{"HeadlessChrome/120", "HeadlessChrome"},
+		// 人类浏览器不命中
+		{"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0 Safari/537.36", ""},
+		{"Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 Mobile/15E148 Safari/604.1", ""},
+		{"", ""},
+	}
+	for _, c := range cases {
+		if got := ClassifyBot(c.ua); got != c.want {
+			t.Errorf("ClassifyBot(%q) = %q, want %q", c.ua, got, c.want)
+		}
+	}
+}