set_expanded

Set expansion state explicitly and re-render.

Single seam through which expansion changes flow, so the screen-level Ctrl+E toggle-all action and the per-row toggle_expand share the same render path. Always re-applies styles.height and re-renders so callers do not need to know whether the state changed — the redundant write is cheap and avoids drift if styles.height was changed externally (CSS reload, theme switch, programmatic edit).