refactor: Update health check service to use undici's fetch for improved HTTP probing and enhance FormFieldSimple component with optional hint prop

apps/api/src/services/health-check-service.ts

@@ -1,5 +1,5 @@
 import { connect } from "node:net";
-import { Agent } from "undici";
+import { Agent, fetch as undiciFetch } from "undici";
 import type { Db } from "@cfdm/db";
 import { repos } from "@cfdm/db";
 import type { HealthCheckTarget, IpHealthState } from "@cfdm/shared";
@@ -67,14 +67,13 @@ async function httpProbe(
   const path = target.path?.trim() || "/";
   const pathWithSlash = path.startsWith("/") ? path : `/${path}`;
   const port = target.port ?? 80;
-  const hostHeader = target.hostname || ip;
   const useTls = port === 443;
-  // For HTTPS probing against a raw IP, set SNI/Host so TLS handshake and vhost routing work.
-  const authorityHost = target.hostname || ip;
-  const url = useTls
-    ? `https://${authorityHost}${pathWithSlash}`
-    : `http://${ip}${pathWithSlash}`;
-  // Custom dispatcher for HTTPS-to-IP: connect to the literal IP, but present hostname via SNI.
+  // For HTTPS on 443, probe via the hostname (URL host = hostname) so TLS SNI, Host header
+  // and any edge/vhost protection (e.g. Cloudflare origin 421 on direct-IP) all line up.
+  // For multi-A records this loses strict per-IP HTTPS granularity — use TCP probe for that.
+  // For plain HTTP we still hit the literal IP (per-record target).
+  const urlHost = useTls ? target.hostname || ip : ip;
+  const url = `${useTls ? "https" : "http"}://${urlHost}${pathWithSlash}`;
   const dispatcher =
     useTls && target.hostname
       ? new Agent({
@@ -85,12 +84,11 @@ async function httpProbe(
         })
       : undefined;
   try {
-    const response = await fetch(url, {
+    const response = await undiciFetch(url, {
       method: "GET",
-      headers: { Host: hostHeader },
+      headers: { Host: target.hostname || ip },
       signal: AbortSignal.timeout(timeoutMs),
       redirect: "manual",
-      // @ts-expect-error undici dispatcher option is not in fetch types
       dispatcher,
     });
     const latency = Date.now() - started;