Role-based access: admin vs superadmin

- Credentials provider now resolves two distinct accounts from env:
    SUPERADMIN_USERNAME / SUPERADMIN_PASSWORD → role "superadmin"
    ADMIN_USERNAME      / ADMIN_PASSWORD      → role "admin"
  The role is carried through the JWT and Session callbacks so the UI
  and API can gate on it. Types extended via types/next-auth.d.ts.
- lib/auth.ts exports requireRole(minRole) and sessionRole(session).
- /api/players POST rejects "op" and "deop" with 403 unless the caller
  is superadmin. All other player actions (whitelist add/remove, ban,
  pardon) remain available to both roles.
- lib/use-role.ts (client hook) exposes role / isSuperadmin / authed
  for UI gating without duplicating session typing.
- PlayerManager: Add-OP button and per-row Deop action are hidden or
  disabled for non-superadmin; when a regular admin is viewing the
  Ops tab, a banner explains the read-only state.
- PlayerDrawer: Make Op / Deop button disabled with tooltip for
  non-superadmin; whitelist, ban, pardon unchanged.
- Navbar: subtle role pill next to the user name ("Super" for
  superadmin amber-tinted, "Admin" for admin).
- Migration note: the existing ADMIN_* credentials now log in as the
  restricted admin role. Set SUPERADMIN_USERNAME + SUPERADMIN_PASSWORD
  in .env.local to retain operator-management ability. A placeholder
  superadmin account was generated in .env.local; the password is in
  the commit terminal output only, not the repo.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/auth.ts

@@ -1,6 +1,31 @@
-import NextAuth from "next-auth";
+import NextAuth, { type Session } from "next-auth";
 import Credentials from "next-auth/providers/credentials";
 
+export type Role = "admin" | "superadmin";
+
+type AccountEntry = { username: string; password: string; role: Role; id: string };
+
+function loadAccounts(): AccountEntry[] {
+  const accounts: AccountEntry[] = [];
+  if (process.env.SUPERADMIN_USERNAME && process.env.SUPERADMIN_PASSWORD) {
+    accounts.push({
+      id: "superadmin",
+      username: process.env.SUPERADMIN_USERNAME,
+      password: process.env.SUPERADMIN_PASSWORD,
+      role: "superadmin",
+    });
+  }
+  if (process.env.ADMIN_USERNAME && process.env.ADMIN_PASSWORD) {
+    accounts.push({
+      id: "admin",
+      username: process.env.ADMIN_USERNAME,
+      password: process.env.ADMIN_PASSWORD,
+      role: "admin",
+    });
+  }
+  return accounts;
+}
+
 export const { handlers, signIn, signOut, auth } = NextAuth({
   providers: [
     Credentials({
@@ -10,16 +35,39 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
         password: { label: "Password", type: "password" },
       },
       async authorize(credentials) {
-        if (
-          credentials?.username === process.env.ADMIN_USERNAME &&
-          credentials?.password === process.env.ADMIN_PASSWORD
-        ) {
-          return { id: "1", name: "Admin" };
+        const username = credentials?.username;
+        const password = credentials?.password;
+        if (typeof username !== "string" || typeof password !== "string") {
+          return null;
+        }
+        for (const acc of loadAccounts()) {
+          if (acc.username === username && acc.password === password) {
+            return {
+              id: acc.id,
+              name: acc.username,
+              role: acc.role,
+            };
+          }
         }
         return null;
       },
     }),
   ],
+  callbacks: {
+    async jwt({ token, user }) {
+      if (user && "role" in user) {
+        token.role = (user as { role?: Role }).role;
+      }
+      return token;
+    },
+    async session({ session, token }) {
+      if (session.user && token.role) {
+        (session.user as Session["user"] & { role?: Role }).role =
+          token.role as Role;
+      }
+      return session;
+    },
+  },
   pages: {
     signIn: "/login",
   },
@@ -28,3 +76,17 @@ export const { handlers, signIn, signOut, auth } = NextAuth({
     maxAge: 24 * 60 * 60,
   },
 });
+
+export async function requireRole(minRole: Role): Promise<Session | null> {
+  const session = await auth();
+  if (!session) return null;
+  const role = (session.user as { role?: Role } | undefined)?.role;
+  if (!role) return null;
+  if (minRole === "superadmin" && role !== "superadmin") return null;
+  return session;
+}
+
+export function sessionRole(session: Session | null | undefined): Role | null {
+  if (!session?.user) return null;
+  return ((session.user as { role?: Role }).role as Role) || null;
+}

lib/use-role.ts

@@ -0,0 +1,16 @@
+"use client";
+
+import { useSession } from "next-auth/react";
+
+export type Role = "admin" | "superadmin";
+
+export function useRole(): { role: Role | null; isSuperadmin: boolean; authed: boolean } {
+  const { data: session, status } = useSession();
+  const role =
+    (session?.user as { role?: Role } | undefined)?.role ?? null;
+  return {
+    role,
+    isSuperadmin: role === "superadmin",
+    authed: status === "authenticated" && !!session,
+  };
+}