feat: replace custom login/signup with NextAuth credentials provider, add signup page using Prisma, update NextAuth config to JWT strategy

pages/api/auth/[...nextauth].js

@@ -1,52 +1,57 @@
 import NextAuth from "next-auth"
 import CredentialsProvider from "next-auth/providers/credentials"
-import { PrismaAdapter } from "@next-auth/prisma-adapter"
 import { PrismaClient } from "@prisma/client"
 import bcrypt from "bcryptjs"
 
 const prisma = new PrismaClient()
 
 export default NextAuth({
-  adapter: PrismaAdapter(prisma),
-  trustHost: true,
   providers: [
     CredentialsProvider({
       name: "Credentials",
       credentials: {
-        username: { label: "Username", type: "text", placeholder: "seu_usuario" },
+        username: { label: "Username", type: "text" },
         password: { label: "Password", type: "password" }
       },
       async authorize(credentials) {
         if (!credentials?.username || !credentials?.password) return null
-        
         const user = await prisma.user.findUnique({
           where: { username: credentials.username }
         })
-
-        if (user && user.password) {
-          const isValid = await bcrypt.compare(credentials.password, user.password)
-          if (isValid) {
-            return { 
-              id: user.id, 
-              email: user.email, 
-              name: user.name || user.username,
-              username: user.username
-            }
-          }
+        if (!user) return null
+        const isValid = await bcrypt.compare(credentials.password, user.password)
+        if (!isValid) return null
+        return {
+          id: user.id,
+          username: user.username,
+          email: user.email,
+          name: user.name,
+          // optional: role, image, etc.
         }
-        return null
       }
     })
   ],
   secret: process.env.NEXTAUTH_SECRET,
-  session: { strategy: "jwt" },
-  pages: {
-    signIn: "/signin",
+  session: {
+    strategy: "jwt",
+    maxAge: 30 * 24 * 60 * 60 // 30 days
   },
   callbacks: {
-    async session({ session, token, user }) {
-      if (session.user) {
-        session.user.id = token.sub
+    async jwt({ token, user }) {
+      if (user) {
+        token.id = user.id
+        token.username = user.username
+        token.email = user.email
+        token.name = user.name
+      }
+      return token
+    },
+    async session({ session, token }) {
+      if (token) {
+        session.user.id = token.id
+        session.user.username = token.username
+        session.user.email = token.email
+        session.user.name = token.name
       }
       return session
     }