fix: move forwardAuth endpoint to /api/theia-auth

NextAuth catches all /api/auth/* routes via [...nextauth] catch-all.
Move the Traefik forwardAuth endpoint to /api/theia-auth to avoid
the conflict. Traefik dynamic config updated to match.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/api/auth/theia-check/route.ts

@@ -1,56 +0,0 @@
-/**
- * GET /api/auth/theia-check
- *
- * Traefik ForwardAuth endpoint for theia.vibnai.com.
- *
- * Traefik calls this URL for every request to the Theia IDE, forwarding
- * the user's Cookie header via authRequestHeaders. We validate the
- * NextAuth session token and return:
- *   200  — session valid, Traefik lets the request through
- *   302  — no session, redirect browser to Vibn login
- */
-
-import { NextRequest, NextResponse } from 'next/server';
-import { getToken } from 'next-auth/jwt';
-
-const APP_URL = process.env.NEXTAUTH_URL ?? 'https://vibnai.com';
-const THEIA_URL = 'https://theia.vibnai.com';
-
-export async function GET(request: NextRequest) {
-  let token: Awaited<ReturnType<typeof getToken>> = null;
-
-  try {
-    token = await getToken({
-      req: request,
-      secret: process.env.NEXTAUTH_SECRET,
-    });
-  } catch {
-    // If token validation throws, treat as unauthenticated
-  }
-
-  if (!token) {
-    // Build a callbackUrl so after login the user lands back in Theia
-    const forwardedHost = request.headers.get('x-forwarded-host');
-    const forwardedProto = request.headers.get('x-forwarded-proto') ?? 'https';
-    const forwardedUri = request.headers.get('x-forwarded-uri') ?? '/';
-
-    const destination = forwardedHost
-      ? `${forwardedProto}://${forwardedHost}${forwardedUri}`
-      : THEIA_URL;
-
-    const loginUrl = `${APP_URL}/auth?callbackUrl=${encodeURIComponent(destination)}`;
-
-    return NextResponse.redirect(loginUrl, { status: 302 });
-  }
-
-  // Session is valid — pass user identity to Theia via response headers
-  // (Traefik forwards these to the upstream if authResponseHeaders is set)
-  return new NextResponse(null, {
-    status: 200,
-    headers: {
-      'X-Auth-User': token.sub ?? '',
-      'X-Auth-Email': (token.email as string) ?? '',
-      'X-Auth-Name': (token.name as string) ?? '',
-    },
-  });
-}