Drop the redundant header row (duplicate percentage badge + collapse
chevron), the "Why this is appropriate/less appropriate:"/"Why this
is incorrect:" heading labels, and the nested sub-box - now that
these cards live inside their own choice's colored border, all of
that was repeating what the color and position already say. Both the
selected-wrong-choice resolved follow-up and the never-selected
distractor cards now just show the plain explanation sentence, with
the leading "Correct."/"Incorrect." verdict word stripped too.
Removing the toggle chevron removes the only way to reach the
collapse/expand behavior, so that machinery (_collapse_resolved_followups,
_toggle_followup_state, the "collapsed" state field) comes out too
rather than linger unreachable.
The choice button above the panel already shows the letter badge,
choice text, and percentage, so repeating them in the panel header
was redundant now that the panel is docked inside the choice's card.
Keeps the collapse toggle, now named FollowupToggle since the old
FollowupSummary button it lived on is gone.
A choice that was crossed out (right-click) and also happened to be
locked as the submitted-wrong choice, or revealed as the correct
answer, silently lost its strikethrough because the percentage-badge
branches took precedence over the elimination check in the same
if/elif chain. Decoupled the two so a choice can show both the
strikethrough and its reveal percentage at once.
hz