fix(dev): point TENANT_REGISTRY_URL at :8090

Unblock local dev: Keycloak owns :8080, so tenant-registry shifts to :8090. Prod is functionally unchanged.

Refs: M5.1

src/lib/tenant-registry.ts

@@ -13,7 +13,7 @@ export type Tenant = {
 };
 
 function baseUrl(): string {
-  return process.env.TENANT_REGISTRY_URL ?? "http://localhost:8080";
+  return process.env.TENANT_REGISTRY_URL ?? "http://localhost:8090";
 }
 
 export async function fetchTenantBySlug(slug: string): Promise<Tenant | null> {