`<module>:view` gates the backoffice sidebar entry, the route, and the API
read all at once, so granting a user another module's list endpoint for a form
dropdown also hands them that module's whole page.
Seed a `:read` twin for every `:view` key and teach the freight guards to
accept it wherever the matching `:view` is required — on GET/HEAD/OPTIONS
only, since class and method guards AND together and a write route without its
own method gate would otherwise be reachable. The frontend never checks
`:read`, which is what keeps the module hidden.
Twins are derived, not hand-written, so a new `:view` gets one for free.
Grants stay hand-curated in iam.position_type_permissions.