Enable branded portal subdomains for each business (portal hub + {business}.talleflow.com)

As a customer, I want my clients to access their portal from a branded Talleflow subdomain so it feels like a dedicated portal for my business, without requiring me to set up my own custom domain. What I want A central portal hub at portal.talleflow.com where I (or my clients) can choose between multiple businesses/portals if needed. A dedicated portal URL for a specific business at {business-slug}.talleflow.com (example: acme.talleflow.com) that takes users directly into that business’s portal experience. How it should behave The hub and each business subdomain should feel like separate portal entry points (no confusing crossover between businesses). If a user opens a link on the “wrong” portal host, they should be redirected to the correct, canonical portal URL for that business while keeping the same page and any query parameters. Emails and notifications that link to the portal should use the correct canonical portal link for that business (so links go to {business-slug}.talleflow.com when available). Important notes / expectations This is not “bring your own domain” (no portal.mycompany.com setup). I only want Talleflow-managed subdomains under talleflow.com. Business slugs should be validated so they are clean, safe, and don’t conflict with reserved names (like portal, app, api, etc.).