feat: Sprint 2 — test taking + results

Backend:
- Models: TestAttempt, AttemptAnswer (migration 002)
- POST /api/attempts: start attempt, shuffle questions/answers,
  hide is_correct, expose is_multiple for UI hints
- POST /api/attempts/{id}/submit: save answers, calculate score,
  strict matching (selected == correct), return full result
- GET /api/attempts/{id}/result: fetch saved result
- Register attempts router in main.py

Frontend:
- api/attempts.ts: types + API functions
- TestTake page: one question at a time, progress bar, timer
  with auto-submit, back navigation controlled by test setting,
  radio/checkbox based on is_multiple
- AttemptResult page: score, pass/fail, per-question breakdown
  with correct/selected/missed answer highlighting
- App.tsx: add /tests/:testId/take and /attempts/:id/result routes
- TestDetail: add "Пройти тест" button

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/models/attempt.py

@@ -0,0 +1,49 @@
+from datetime import datetime
+
+from sqlalchemy import Boolean, DateTime, Float, ForeignKey, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class TestAttempt(Base):
+    __tablename__ = "test_attempts"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    test_id: Mapped[int] = mapped_column(Integer, ForeignKey("tests.id"), nullable=False)
+    started_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now()
+    )
+    finished_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    score: Mapped[float | None] = mapped_column(Float, nullable=True)  # процент 0–100
+    passed: Mapped[bool | None] = mapped_column(Boolean, nullable=True)
+    correct_count: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    total_count: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    # in_progress | finished
+    status: Mapped[str] = mapped_column(String(20), default="in_progress", nullable=False)
+
+    test: Mapped["Test"] = relationship("Test")  # type: ignore[name-defined]
+    answers: Mapped[list["AttemptAnswer"]] = relationship(
+        "AttemptAnswer", back_populates="attempt", cascade="all, delete-orphan"
+    )
+
+
+class AttemptAnswer(Base):
+    """Одна запись = один выбранный вариант ответа сотрудника."""
+
+    __tablename__ = "attempt_answers"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    attempt_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("test_attempts.id"), nullable=False
+    )
+    question_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("questions.id"), nullable=False
+    )
+    answer_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("answers.id"), nullable=False
+    )
+
+    attempt: Mapped["TestAttempt"] = relationship("TestAttempt", back_populates="answers")
+    answer: Mapped["Answer"] = relationship("Answer")  # type: ignore[name-defined]