fix(portal): add invitation links and correct customer login routing

backend/src/routes/auth/auth.ts

@@ -7,6 +7,7 @@ import { authUsers } from "../../../db/schema";
 import { authTenantUsers } from "../../../db/schema";
 import { tenants } from "../../../db/schema";
 import { and, eq } from "drizzle-orm";
+import { resolveLoginTenant } from "../../utils/loginTenant";
 import {
     createAccessToken,
     issueRefreshToken,
@@ -127,7 +128,7 @@ export default async function authRoutes(server: FastifyInstance) {
             return reply.code(401).send({ error: "Invalid credentials" });
         }
 
-        const tenantId = req.tenant?.id ? Number(req.tenant.id) : null;
+        const tenantId = await resolveLoginTenant(server, user.id, req.tenant?.id ? Number(req.tenant.id) : null);
         const token = createAccessToken(user, tenantId);
         const refreshToken = await issueRefreshToken(server, user.id, tenantId);