feat: add support for OAuth-only login mode and update configuration handling

app/api/auth/session/route.ts

@@ -14,6 +14,10 @@ const COOKIE_OPTIONS = {
 
 export async function POST(request: NextRequest) {
   try {
+    if (process.env.OAUTH_ENABLED === 'true' && process.env.OAUTH_ONLY === 'true') {
+      return NextResponse.json({ error: 'Basic authentication is disabled' }, { status: 403 });
+    }
+
     const { serverUrl, username, password } = await request.json();
     if (!serverUrl || !username || !password) {
       return NextResponse.json({ error: 'Missing required fields' }, { status: 400 });

app/api/config/route.ts

@@ -19,6 +19,7 @@ export async function GET() {
     appName: process.env.APP_NAME || process.env.NEXT_PUBLIC_APP_NAME || 'Webmail',
     jmapServerUrl: process.env.JMAP_SERVER_URL || process.env.NEXT_PUBLIC_JMAP_SERVER_URL || '',
     oauthEnabled: process.env.OAUTH_ENABLED === 'true',
+    oauthOnly: process.env.OAUTH_ENABLED === 'true' && process.env.OAUTH_ONLY === 'true',
     oauthClientId: process.env.OAUTH_CLIENT_ID || '',
     oauthIssuerUrl: process.env.OAUTH_ISSUER_URL || '',
     rememberMeEnabled: !!process.env.SESSION_SECRET,