Adds a pencil icon button next to each participant's delete button. Clicking
it switches the row into edit mode with an input field, a save (checkmark) and
cancel (X) button. Escape also cancels. Submits via intent="update-name" and
validates uniqueness within the season before persisting.
https://claude.ai/code/session_01Q94DWQ1HZEB9PJhGMArU8D