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.go

@@ -0,0 +1,69 @@
+package service
+
+import "strings"
+
+// botSignatures 爬虫 UA 特征（小写子串 → 展示名），覆盖搜索引擎 / SEO 工具 / AI 爬虫 / 命令行客户端
+var botSignatures = []struct {
+	token string
+	name  string
+}{
+	{"googlebot", "Googlebot"},
+	{"google-inspectiontool", "Google Inspection Tool"},
+	{"apis-google", "Googlebot"},
+	{"bingbot", "bingbot"},
+	{"baiduspider", "Baiduspider"},
+	{"sogou", "Sogou spider"},
+	{"yisou", "YisouSpider"},
+	{"360spider", "360Spider"},
+	{"haosouspider", "HaosouSpider"},
+	{"bytespider", "Bytespider"},
+	{"duckduckbot", "DuckDuckBot"},
+	{"applebot", "Applebot"},
+	{"petalbot", "PetalBot"},
+	{"yandexbot", "YandexBot"},
+	{"semrushbot", "SemrushBot"},
+	{"ahrefsbot", "AhrefsBot"},
+	{"mj12bot", "MJ12bot"},
+	{"dotbot", "DotBot"},
+	{"gptbot", "GPTBot"},
+	{"claudebot", "ClaudeBot"},
+	{"claude-web", "ClaudeBot"},
+	{"ccbot", "CCBot"},
+	{"perplexitybot", "PerplexityBot"},
+	{"amazonbot", "Amazonbot"},
+	{"facebookexternalhit", "facebookexternalhit"},
+	{"twitterbot", "Twitterbot"},
+	{"slackbot", "Slackbot"},
+	{"discordbot", "Discordbot"},
+	{"linkedinbot", "LinkedInBot"},
+	{"curl/", "curl"},
+	{"wget", "Wget"},
+	{"python-requests", "python-requests"},
+	{"python-urllib", "python-urllib"},
+	{"httpclient", "HTTP Client"},
+	{"go-http-client", "Go-http-client"},
+	{"java/", "Java Client"},
+	{"okhttp", "OkHttp"},
+	{"scrapy", "Scrapy"},
+	{"headlesschrome", "HeadlessChrome"},
+	{"puppeteer", "Puppeteer"},
+	{"phantomjs", "PhantomJS"},
+	{"bot;", "Bot"},
+	{"spider", "Spider"},
+	{"crawler", "Crawler"},
+}
+
+// ClassifyBot 根据 User-Agent 判定爬虫；命中返回爬虫展示名，否则返回空串。
+// 纯小写包含匹配，便于单测。
+func ClassifyBot(ua string) string {
+	low := strings.ToLower(strings.TrimSpace(ua))
+	if low == "" {
+		return ""
+	}
+	for _, sig := range botSignatures {
+		if strings.Contains(low, sig.token) {
+			return sig.name
+		}
+	}
+	return ""
+}