Himalaya mail capability

dev.formless.himalaya-dashboard exposes inbox list, search, and read operations through the typed Host-owned dev.formless.email capability.

Host invokes Himalaya with fixed arguments. The Canvas receives typed message rows and content; it does not mount mail credentials or construct arbitrary commands. Credentials can remain outside plugin memory when the Host-owned service capability performs the sensitive operation.

The example demonstrates why a centralized typed Host API is useful for selected high-value boundaries: it protects secrets and constrains intent. It is not a general relay and does not accept arbitrary URLs or argv.