feat: add dnsmasq DNS record admin UI

- store records in SQLite via built-in node:sqlite, no native deps
- wrap DB reads in await io() so they stay out of the static shell
- add CRUD pages backed by Server Actions with per-request data
- generate managed config and restart container via Docker socket
- add /resolve page to query dnsmasq for A and CNAME records
- add Dockerfile and compose setup with shared config volume

lib/docker.ts

@@ -0,0 +1,92 @@
+import { existsSync } from "node:fs"
+import http from "node:http"
+import { env } from "./env"
+
+export type ReloadOutcome =
+  | { status: "restarted"; detail: string }
+  | { status: "skipped"; detail: string }
+  | { status: "failed"; detail: string }
+
+interface DockerResponse {
+  statusCode: number
+  body: string
+}
+
+const REQUEST_TIMEOUT_MS = 5000
+
+function dockerRequest(socketPath: string, requestPath: string): Promise<DockerResponse> {
+  return new Promise((resolve, reject) => {
+    const request = http.request(
+      {
+        socketPath,
+        path: requestPath,
+        method: "POST",
+        headers: { Host: "localhost", Accept: "application/json" },
+      },
+      (response) => {
+        let body = ""
+        response.setEncoding("utf8")
+        response.on("data", (chunk) => {
+          body += chunk
+        })
+        response.on("end", () => {
+          resolve({ statusCode: response.statusCode ?? 0, body })
+        })
+      }
+    )
+
+    request.on("error", reject)
+    request.setTimeout(REQUEST_TIMEOUT_MS, () => {
+      request.destroy(new Error(`Docker API 请求超时（${REQUEST_TIMEOUT_MS}ms）`))
+    })
+    request.end()
+  })
+}
+
+function failureReason(error: unknown): string {
+  if (error instanceof Error) return error.message
+  return String(error)
+}
+
+/**
+ * Restart the dnsmasq container over the Docker socket.
+ *
+ * Never throws: hosts without a Docker socket (e.g. developing on Windows) get a "skipped"
+ * outcome so the UI can report it instead of blowing up.
+ */
+export async function restartDnsmasqContainer(): Promise<ReloadOutcome> {
+  if (!env.containerName) {
+    return { status: "skipped", detail: "未配置 DNSMASQ_CONTAINER_NAME，跳过重启" }
+  }
+
+  if (!existsSync(env.dockerSocket)) {
+    return { status: "skipped", detail: `Docker socket 不存在：${env.dockerSocket}，跳过重启` }
+  }
+
+  try {
+    const response = await dockerRequest(
+      env.dockerSocket,
+      `/containers/${encodeURIComponent(env.containerName)}/restart`
+    )
+
+    if (response.statusCode >= 200 && response.statusCode < 300) {
+      return { status: "restarted", detail: `容器 ${env.containerName} 已重启` }
+    }
+
+    if (response.statusCode === 404) {
+      return { status: "failed", detail: `找不到容器 ${env.containerName}` }
+    }
+
+    if (response.statusCode === 403) {
+      return { status: "failed", detail: "Docker API 拒绝访问，请检查 socket 权限" }
+    }
+
+    const remote = response.body.trim().slice(0, 200)
+    return {
+      status: "failed",
+      detail: `Docker API 返回 ${response.statusCode}${remote ? `：${remote}` : ""}`,
+    }
+  } catch (error) {
+    return { status: "failed", detail: failureReason(error) }
+  }
+}