two questions per teaching unit: predict → teach → check (owner 2026-10-03)

The teaching cycle gains its motivation question. The teach quiz schema
now carries a REQUIRED type field — predict (posed before the teaching,
arrives open, the learner predicts the next step) or check (posed after,
arrives collapsed behind the reveal). The prober's quiz stays role-less.

- core: quizInputObject.type union + normalizeQuizType + the reveal law
  as pure quizNeedsReveal; QuestionData.questionType; note → thinking
  rename (legacy reads fold back); readingThinking channel on answers;
  compactAnswerForModel emits thinking / thinkingWhileReading
- tools: descriptions stripped to mechanics — QUIZ_OPTION_CRAFT and
  EXPLAIN_DOCTRINE deleted, doctrine moved to the prompt layer
  (reverses the 2026-09-27 placement, owner 2026-10-03); shared
  quizDescription/explainDescription builders differ only in deltas
- prompts: shared/20-question-tools.md rewritten (option craft,
  transcribed-speech leniency, the two thinking channels); new
  teacher/28-predictions.md (cycle, roles, skip rule, resolution law);
  20-teaching + 30-question-principles scoped to the new taxonomy
- UI: predictions render open with a Prediction eyebrow, verdict shows
  but the explanation tucks behind a toggle; the reading-thinking field
  mounts while a check waits (dictation claims it until reveal);
  answered card separates thinking vs thinking-while-reading blocks

tests/session-core.test.ts

@@ -923,7 +923,7 @@ describe("newAnswerResult two audiences", () => {
 			explanation: "Mercury orbits closest.",
 			createdAt: "2026-01-01T00:00:00Z",
 		};
-		const full = buildAnswer(qd, { values: ["mercury"], confidence: 70, note: "guessed" });
+		const full = buildAnswer(qd, { values: ["mercury"], confidence: 70, thinking: "guessed" });
 		const msg = newAnswerResult("call-1", "quiz", full);
 		const modelSees = JSON.parse((msg.content as { type: "text"; text: string }[])[0]!.text);
 		assert.deepEqual(modelSees, {
@@ -931,7 +931,7 @@ describe("newAnswerResult two audiences", () => {
 			answers: [{ index: 1, label: "Mercury" }],
 			correct: true,
 			confidence: 70,
-			note: "guessed",
+			thinking: "guessed",
 		});
 		assert.equal(msg.details, full, "details is the full QuestionAnswerData verbatim");
 		assert.equal((msg.details as { questionText?: string }).questionText, "Which planet is closest to the Sun?");