Wrap the radio-button options vector in `mf/with-memo []` so the
vector allocation and `(tr ...)` calls happen once per component
mount instead of on every render.
Also document the translation memoization rule in frontend/AGENTS.md:
`(tr ...)` must never be called at namespace level (locale is
runtime-only), and static option lists should always be wrapped in
`mf/with-memo []`.
Signed-off-by: Andrey Antukh <niwi@niwi.nz>