refactor: migrate contact form to TanStack Form

- Replace manual state management with @tanstack/react-form
- Add proper Field/FieldLabel components for accessibility
- Simplify server action (remove useActionState signature)
- Remove use-debounce dependency
- Update PGP key links and minor styling tweaks

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/server/contact.ts

@@ -6,49 +6,49 @@ import { ContactSchema } from "@/lib/schemas/contact";
 import siteConfig from "@/lib/config/site";
 import { checkBotId } from "botid/server";
 
-// Schema and type now imported from shared validation module
-
-export type ContactState = {
+export type ContactResult = {
   success: boolean;
   message: string;
   errors?: Record<string, string[]>;
 };
 
-export const send = async (state: ContactState, payload: FormData): Promise<ContactState> => {
+export const sendContactForm = async (formData: FormData): Promise<ContactResult> => {
   // TODO: remove after debugging why automated spam entries are causing 500 errors
-  console.debug("[server/contact] received payload:", payload);
+  console.debug("[server/contact] received payload:", formData);
 
   // BotID server-side verification
   const verification = await checkBotId();
   if (verification.isBot) {
     console.warn("[server/contact] botid verification failed:", verification);
-    throw new Error("Bot check failed");
+    return {
+      success: false,
+      message: "Verification failed. Please try again.",
+    };
+  }
+
+  const parsed = ContactSchema.safeParse(Object.fromEntries(formData));
+
+  if (!parsed.success) {
+    return {
+      success: false,
+      message: "Please make sure all fields are filled in correctly.",
+      errors: parsed.error.flatten().fieldErrors,
+    };
   }
 
   try {
-    const data = ContactSchema.safeParse(Object.fromEntries(payload));
-
-    if (!data.success) {
-      return {
-        success: false,
-        message: "Please make sure all fields are filled in.",
-        errors: data.error.flatten().fieldErrors,
-      };
-    }
-
     if (env.RESEND_FROM_EMAIL === "onboarding@resend.dev") {
       // https://resend.com/docs/api-reference/emails/send-email
       console.warn("[server/contact] 'RESEND_FROM_EMAIL' is not set, falling back to onboarding@resend.dev.");
     }
 
-    // send email
     const resend = new Resend(env.RESEND_API_KEY);
     await resend.emails.send({
-      from: `${data.data.name} <${env.RESEND_FROM_EMAIL || "onboarding@resend.dev"}>`,
-      replyTo: `${data.data.name} <${data.data.email}>`,
+      from: `${parsed.data.name} <${env.RESEND_FROM_EMAIL || "onboarding@resend.dev"}>`,
+      replyTo: `${parsed.data.name} <${parsed.data.email}>`,
       to: [env.RESEND_TO_EMAIL],
       subject: `[${siteConfig.name}] Contact Form Submission`,
-      text: data.data.message,
+      text: parsed.data.message,
     });
 
     return { success: true, message: "Thanks! You should hear from me soon." };