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-step-state-20260906.test.ts

@@ -55,10 +55,11 @@ test("step state parser rejects forbidden certainty words", () => {
   assert.doesNotMatch(blob, /概率|置信度|确定/);
 });
 
-test("chat renders rectification-step-state above the composer", () => {
+test("chat does not render the step-state strip above the composer", () => {
   const chat = readFileSync(new URL("../src/components/rectification-agentic-chat.tsx", import.meta.url), "utf8");
   const route = readFileSync(new URL("../src/app/api/rectification/cases/[caseId]/route.ts", import.meta.url), "utf8");
-  assert.match(chat, /rectification-step-state/);
+  assert.doesNotMatch(chat, /rectification-step-state/);
+  assert.doesNotMatch(chat, /下一步：\{stepState\.next\}/);
   assert.match(chat, /rectification-composer-meta/);
   assert.match(route, /step_state: stepStateFromCaseDossier/);
 });

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.

frontend/tests/rectification-v9-contracts.test.ts

@@ -235,9 +235,9 @@ test("shouldStartOpening is server-owned: only freshly created never-started cas
   assert.equal(shouldStartOpening("readonly", 0), false);
 });
 
-test("case snapshot includes step_state", () => {
+test("case snapshot includes step_state without a composer strip", () => {
   const route = readFileSync(new URL("../src/app/api/rectification/cases/[caseId]/route.ts", import.meta.url), "utf8");
   const chat = readFileSync(new URL("../src/components/rectification-agentic-chat.tsx", import.meta.url), "utf8");
   assert.match(route, /step_state: stepStateFromCaseDossier\(dossier\)/);
-  assert.match(chat, /rectification-step-state/);
+  assert.doesNotMatch(chat, /rectification-step-state/);
 });