fix(rectification): hide option hover impact and composer step strip (BUG-575)

Hovering A/B/C/D rewrote a leading/lagging time line and made the card flicker; the step-state sentence above the composer was instructional filler, not something the user needed to answer.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/tests/rectification-surface-contract.test.ts

@@ -136,6 +136,9 @@ test("the choice card confirms the tap and the board's first state shows the dec
   assert.match(choiceCard, /data-selected=\{selectedKey === option\.key \? "true" : "false"\}/);
   assert.match(choiceCard, /rectification-choice-card__pending/);
   assert.match(choiceCard, /InlineSpinner size=\{12\}/);
+  assert.doesNotMatch(choiceCard, /onMouseEnter/);
+  assert.doesNotMatch(choiceCard, /rectification-choice-impact/);
+  assert.doesNotMatch(choiceCard, /hoveredKey/);
   assert.doesNotMatch(styles, /\.rectification-choice-card__selected/);
   assert.match(styles, /\.rectification-choice-card__pending \{/);
   // BUG-518: scoring cards do not render 先这样，先看当前范围; reverse_verify still has 这题跳过.