Function render_mem_changed_block 

pub fn render_mem_changed_block(notices: &[MemChangedNotice]) -> String

Render a human-readable mem_changed block for markdown CLI output. Empty when no reload happened. Names memstead changes-since (never memstead diff) for the follow-up, matching the cross-surface recovery contract. (Always compiled; on lean notices is always empty, so this returns the empty string.)