Rework capabilities to avoid assumptions about missing tokens

Rework capabilities to avoid assumptions about missing tokens

The logic about missing tokens implying logged in users (and that
all logged in users have access to any method protected by a token
capability) is correct. However, I believe it is both confusing and
brittle, and leaves a security-related door ajar for future foot-gun
incidents.

Instead, apply Abilities as normal, and keep the Capabilities
involvement only for situations where a token is provided. This
reduces the cognitive burden when considering Abilities in isolation.