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/graph.test.ts

@@ -185,7 +185,7 @@ function fixtureMessages(): LhMessage[] {
 			quizPart(
 				"call-3",
 				{ question: "Q3", nodeId: "alpha", options: [{ label: "a" }, { label: "b" }], correctAnswer: "a", explanation: "e" },
-				answer({ questionText: "Q3 text", correct: true, note: "recalled the diagram", answeredAt: "2026-08-22T02:00:00.000Z" }),
+				answer({ questionText: "Q3 text", correct: true, thinking: "recalled the diagram", answeredAt: "2026-08-22T02:00:00.000Z" }),
 			),
 		]),
 		assistant("a4", [