Drop useEffect from VerifyCodeForm; replace tick-based countdown

The per-second countdown was the only thing pulling useEffect into this
component, in violation of the project rule (CLAUDE.md: avoid useEffect,
prefer event handlers). The hook was driving a tick purely so we could
show "Resend in 28s" / "27s" / ... — none of which is load-bearing.

Replace it with a single setTimeout fired from the resend event handler
that flips resendStatus from "cooldown" back to "idle" after 30 seconds.
The button stays disabled with "Code sent — wait a moment" instead of
showing a live countdown. Same blocking signal, no hook needed.

While here, split the single status enum into verifyStatus + resendStatus
so the verify button no longer wrongly disables during a resend cooldown
(latent bug from the previous shape).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/auth/verify-code/VerifyCodeForm.tsx

@@ -1,36 +1,33 @@
 "use client";
 
-import { useEffect, useRef, useState } from "react";
+import { useRef, useState } from "react";
 import { signIn } from "next-auth/react";
 import { useRouter } from "next/navigation";
 import { Button } from "@/app/shadcn_components/ui/button";
 import { Input } from "@/app/shadcn_components/ui/input";
 
-const RESEND_COOLDOWN_SECONDS = 30;
+const RESEND_COOLDOWN_MS = 30_000;
 
-type Status = "idle" | "verifying" | "resending";
+type VerifyStatus = "idle" | "verifying";
+type ResendStatus = "idle" | "resending" | "cooldown";
 
 export default function VerifyCodeForm({ email }: { email: string }) {
   const router = useRouter();
   const [code, setCode] = useState("");
-  const [status, setStatus] = useState<Status>("idle");
+  const [verifyStatus, setVerifyStatus] = useState<VerifyStatus>("idle");
+  const [resendStatus, setResendStatus] = useState<ResendStatus>("idle");
   const [error, setError] = useState<string | null>(null);
-  const [resendCountdown, setResendCountdown] = useState(0);
   const [resendNotice, setResendNotice] = useState<string | null>(null);
   const inFlightRef = useRef(false);
 
-  // Resend cooldown timer
-  useEffect(() => {
-    if (resendCountdown <= 0) return;
-    const id = setTimeout(() => setResendCountdown((s) => s - 1), 1000);
-    return () => clearTimeout(id);
-  }, [resendCountdown]);
+  const isWorking =
+    verifyStatus === "verifying" || resendStatus === "resending";
 
   async function submitCode(value: string) {
     if (inFlightRef.current) return;
     if (!/^\d{6}$/.test(value)) return;
     inFlightRef.current = true;
-    setStatus("verifying");
+    setVerifyStatus("verifying");
     setError(null);
 
     const res = await signIn("email-code", {
@@ -46,7 +43,7 @@ export default function VerifyCodeForm({ email }: { email: string }) {
       return;
     }
 
-    setStatus("idle");
+    setVerifyStatus("idle");
     setCode("");
     setError(
       "That code didn't match. Check the latest email — older codes stop working as soon as you request a new one.",
@@ -62,25 +59,33 @@ export default function VerifyCodeForm({ email }: { email: string }) {
   }
 
   async function handleResend() {
-    if (resendCountdown > 0 || status === "resending") return;
-    if (!email) return;
-    setStatus("resending");
+    if (isWorking || resendStatus === "cooldown" || !email) return;
+    setResendStatus("resending");
     setError(null);
     setResendNotice(null);
 
     const res = await signIn("email", { email, redirect: false });
 
-    setStatus("idle");
     if (res?.error) {
+      setResendStatus("idle");
       setError(
         "We couldn't send a new code right now. Wait a minute and try again.",
       );
       return;
     }
+
     setResendNotice("A new code is on its way. Older codes stop working.");
-    setResendCountdown(RESEND_COOLDOWN_SECONDS);
+    setResendStatus("cooldown");
+    setTimeout(() => setResendStatus("idle"), RESEND_COOLDOWN_MS);
   }
 
+  const resendLabel =
+    resendStatus === "resending"
+      ? "Sending…"
+      : resendStatus === "cooldown"
+        ? "Code sent — wait a moment"
+        : "Resend code";
+
   return (
     <div className="space-y-4 text-left">
       <div>
@@ -98,7 +103,7 @@ export default function VerifyCodeForm({ email }: { email: string }) {
           onChange={(e) => handleChange(e.target.value)}
           placeholder="••••••"
           className="h-12 text-center text-2xl tracking-[0.5em] font-mono"
-          disabled={status === "verifying"}
+          disabled={verifyStatus === "verifying"}
           autoFocus
         />
       </div>
@@ -106,10 +111,10 @@ export default function VerifyCodeForm({ email }: { email: string }) {
       <Button
         type="button"
         onClick={() => submitCode(code)}
-        disabled={status !== "idle" || code.length !== 6}
+        disabled={isWorking || code.length !== 6}
         className="bg-brandbrown hover:bg-hoverblue w-full text-base py-3"
       >
-        {status === "verifying" ? "Verifying…" : "Sign in"}
+        {verifyStatus === "verifying" ? "Verifying…" : "Sign in"}
       </Button>
 
       <div className="text-center text-sm space-y-2">
@@ -120,19 +125,12 @@ export default function VerifyCodeForm({ email }: { email: string }) {
         <button
           type="button"
           onClick={handleResend}
-          disabled={
-            resendCountdown > 0 || status === "resending" || !email
-          }
+          disabled={isWorking || resendStatus === "cooldown" || !email}
           className="text-brandblue hover:underline disabled:text-gray-400 disabled:no-underline"
         >
-          {status === "resending"
-            ? "Sending…"
-            : resendCountdown > 0
-              ? `Resend code in ${resendCountdown}s`
-              : "Resend code"}
+          {resendLabel}
         </button>
       </div>
-
     </div>
   );
 }