refac: hardening pass with multiple overhauls

docs/architecture.md

@@ -21,6 +21,13 @@ api/  ──▶  internal/infrastructure/useCases  ──▶  internal/domain
 
 Nothing under `internal/` imports `api/`.
 
+### Delivery packages
+
+| Package | Role |
+|---|---|
+| `api/handlers/user` | Authenticated user endpoints: profile update (`UpdateMe`) and the users list with invitations (`CreateInvite`, `ListUsers`). |
+| `api/pkg/publicuser` | `PublicUser`, the JSON shape of a user with no password, codes or token version. `publicuser.New` converts a domain `user.User`, so handlers never serialise the domain struct directly. |
+
 ## Frontend ↔ backend
 
 ```