Function collect_context_items 

pub fn collect_context_items(
    include_defaults: bool,
    caps: ContextMenuCaps,
    hook_rows: Vec<Vec<ContextMenuItem>>,
) -> Vec<ContextMenuItem>

Merges defaults with hook-contributed rows.

• When include_defaults is false, only hook rows are used.
• Hook rows append in order after the defaults.
• A hook row whose id matches a default (or an earlier hook row) replaces it in place, keeping the original position.
• The trailing divider on the defaults block is dropped when no hook rows follow, so a defaults-only menu has no stray separator.