Add phone and birthday fields to User model with admin editor

- Add phone/birthday columns via Prisma migration
- Admin user page shows phone and birthday with inline edit UI
- UserContactEditor client component for editing contact info
- updateUserContact server action with admin-only guard

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/admin/users/[userId]/actions.ts

@@ -41,6 +41,21 @@ export async function bulkGrantAccess(
   revalidatePath(`/admin/users/${userId}`);
 }
 
+export async function updateUserContact(
+  userId: string,
+  data: { phone: string; birthday: string }
+) {
+  await requireAdmin();
+  await prisma.user.update({
+    where: { id: userId },
+    data: {
+      phone: data.phone.trim() || null,
+      birthday: data.birthday ? new Date(data.birthday) : null,
+    },
+  });
+  revalidatePath(`/admin/users/${userId}`);
+}
+
 export async function revokeUserAccess(userId: string, courseId: string) {
   const session = await requireAdmin();
   await prisma.courseEnrollment.delete({

src/app/admin/users/[userId]/page.tsx

@@ -2,6 +2,7 @@ import { prisma } from "@/lib/prisma";
 import { notFound } from "next/navigation";
 import Link from "next/link";
 import { UserEnrollmentManager } from "@/components/admin/user-enrollment-manager";
+import { UserContactEditor } from "@/components/admin/user-contact-editor";
 
 interface Props {
   params: Promise<{ userId: string }>;
@@ -47,7 +48,7 @@ export default async function UserPage({ params }: Props) {
       </nav>
 
       {/* User info */}
-      <section className="card-aubade p-6 mb-6">
+      <section className="card-aubade p-6 mb-6 space-y-4">
         <div className="flex items-start justify-between">
           <div>
             <h1 className="text-xl font-bold">{user.name}</h1>
@@ -60,6 +61,13 @@ export default async function UserPage({ params }: Props) {
             </span>
           </div>
         </div>
+        <div style={{ borderTop: "2px solid var(--border)", paddingTop: "1rem" }}>
+          <UserContactEditor
+            userId={userId}
+            phone={user.phone ?? null}
+            birthday={user.birthday ?? null}
+          />
+        </div>
       </section>
 
       {/* Enrollments + bulk grant */}