Build a Contact Form with Server Action

Problem/Feature Description

Build a Next.js App Router page with a contact form. When submitted, the form should save the message to an in-memory store and show a success message.

Form fields:

• Name (required, min 2 characters)
• Email (required, must be valid email format)
• Subject (required)
• Message (required, min 10 characters)

The page should:

• Show the form at /contact
• Display validation errors inline next to each field
• Show a success message after submission
• Show a loading state while submitting
• Also list previously submitted messages at /contact/messages (admin page)

Output Specification

Produce:

• app/contact/page.tsx -- the contact form page
• app/contact/messages/page.tsx -- page listing submitted messages
• Server Action for handling the form submission
• package.json with dependencies

You may create additional files as needed.