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

frontend/app/admin/analytics/ui.tsx

@@ -0,0 +1,166 @@
+"use client";
+
+import { useEffect, useState, type ReactNode } from "react";
+import { onDocumentVisible } from "@/lib/visibilityReconcile";
+
+/** 事件类型中文标签 */
+export function kindLabel(kind: string): string {
+  switch (kind) {
+    case "pageview":
+      return "浏览";
+    case "bot":
+      return "爬虫";
+    case "probe":
+      return "探测";
+    default:
+      return kind || "-";
+  }
+}
+
+/** 来源类别中文标签 */
+export function refKindLabel(kind: string): string {
+  switch (kind) {
+    case "direct":
+      return "直接访问";
+    case "internal":
+      return "站内";
+    case "search":
+      return "搜索引擎";
+    case "social":
+      return "社交";
+    case "external":
+      return "外部链接";
+    default:
+      return kind || "-";
+  }
+}
+
+export function deviceLabel(d: string): string {
+  switch (d) {
+    case "computer":
+      return "电脑";
+    case "mobile":
+      return "手机";
+    case "tablet":
+      return "平板";
+    default:
+      return d || "未知";
+  }
+}
+
+export function formatBytes(n: number): string {
+  if (!Number.isFinite(n) || n <= 0) return "0 B";
+  const units = ["B", "KB", "MB", "GB", "TB"];
+  let v = n;
+  let i = 0;
+  while (v >= 1024 && i < units.length - 1) {
+    v /= 1024;
+    i++;
+  }
+  return `${v >= 100 ? Math.round(v) : v.toFixed(1)} ${units[i]}`;
+}
+
+export function formatInt(n: number): string {
+  return new Intl.NumberFormat("zh-CN").format(n);
+}
+
+/** 简单加载/错误占位（居中卡片内文本） */
+export function StatsState({ loading, error }: { loading?: boolean; error?: string }) {
+  if (loading) {
+    return (
+      <div className="panel p-10 text-center text-[13px]" style={{ color: "var(--ink-3)" }}>
+        正在加载…
+      </div>
+    );
+  }
+  if (error) {
+    return (
+      <div className="panel p-10 text-center text-[13px]" style={{ color: "var(--danger)" }}>
+        {error}
+      </div>
+    );
+  }
+  return null;
+}
+
+export function TableEmpty({ text = "暂无数据" }: { text?: string }) {
+  return (
+    <p className="py-8 text-center text-[13px]" style={{ color: "var(--ink-3)" }}>
+      {text}
+    </p>
+  );
+}
+
+/** 15 秒轮询 + 回前台即拉；返回手动 reload */
+export function usePolling(load: () => void, intervalMs = 15_000) {
+  const [, setTick] = useState(0);
+  useEffect(() => {
+    load();
+    const timer = setInterval(load, intervalMs);
+    const off = onDocumentVisible(load);
+    return () => {
+      clearInterval(timer);
+      off();
+    };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [intervalMs]);
+  return () => setTick((t) => t + 1);
+}
+
+/** 7/30 日区间切换段控件（各 Tab 复用） */
+export function RangeSegmented({
+  value,
+  onChange,
+}: {
+  value: "7d" | "30d";
+  onChange: (v: "7d" | "30d") => void;
+}) {
+  return (
+    <div className="flex items-center gap-1.5" role="tablist" aria-label="统计区间">
+      {(
+        [
+          { key: "7d", label: "近 7 日" },
+          { key: "30d", label: "近 30 日" },
+        ] as const
+      ).map((o) => (
+        <button
+          key={o.key}
+          type="button"
+          role="tab"
+          aria-selected={value === o.key}
+          onClick={() => value !== o.key && onChange(o.key)}
+          className="admin-seg"
+        >
+          {o.label}
+        </button>
+      ))}
+    </div>
+  );
+}
+
+export function CardShell({
+  title,
+  hint,
+  actions,
+  children,
+}: {
+  title: string;
+  hint?: string;
+  actions?: ReactNode;
+  children: ReactNode;
+}) {
+  return (
+    <div className="panel p-4 sm:p-5">
+      <div className="flex items-start justify-between gap-2 mb-3">
+        <div className="min-w-0">
+          <h3 className="text-[14.5px] font-semibold" style={{ color: "var(--ink)" }}>
+            {title}
+          </h3>
+          {hint ? <p className="meta text-[11.5px] mt-0.5">{hint}</p> : null}
+        </div>
+        {actions}
+      </div>
+      {children}
+    </div>
+  );
+}