feat(bot): модель данных, миграции Alembic, FSM в БД, TTL-чистка

- app/db/models.py: 13 таблиц (ARCHITECTURE §2.10); перечисления — VARCHAR + CHECK,
  JSON → JSONB на Postgres, BIGINT/INTEGER-ключи для SQLite
- миграция 0001 (автогенерация + ручная чистка: импорт sa.Text, дубли CHECK)
- миграции применяются при старте бота программно (app.db.migrate), script_location из пакета
- SqlStorage: FSM aiogram поверх fsm_state — состояние переживает рестарт (перенесено из #4)
- cleanup_loop: истёкшие черновики, снимки контейнеров и попытки входа старше суток
- тесты: upgrade/downgrade, дрейф моделей и миграций, CHECK, CASCADE, FSM, чистка

Refs #5

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/db/test_migrations.py

@@ -0,0 +1,82 @@
+from datetime import timedelta
+
+import pytest
+from alembic.autogenerate import compare_metadata
+from alembic.migration import MigrationContext
+from sqlalchemy import inspect, text
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.ext.asyncio import AsyncEngine
+
+from app.db.migrate import downgrade, upgrade
+from app.db.models import Base, ChangeOp, Draft, DraftChange, User, utcnow
+from app.db.session import SessionMaker, make_engine
+
+TABLES = {
+    "users",
+    "invites",
+    "access_attempts",
+    "fsm_state",
+    "drafts",
+    "draft_changes",
+    "pushes",
+    "pipeline_runs",
+    "container_snapshots",
+    "alerts",
+    "alert_deliveries",
+    "log_queries",
+    "agent_requests",
+}
+
+
+async def table_names(engine: AsyncEngine) -> set[str]:
+    async with engine.connect() as conn:
+        return set(await conn.run_sync(lambda c: inspect(c).get_table_names())) - {"alembic_version"}
+
+
+async def test_upgrade_creates_all_tables(engine: AsyncEngine) -> None:
+    assert await table_names(engine) == TABLES
+
+
+async def test_models_match_migrations(engine: AsyncEngine) -> None:
+    # A model change without a migration shows up here as a non-empty diff.
+    async with engine.connect() as conn:
+        diff = await conn.run_sync(lambda c: compare_metadata(MigrationContext.configure(c), Base.metadata))
+    assert diff == []
+
+
+async def test_downgrade_to_base_and_back() -> None:
+    eng = make_engine("sqlite+aiosqlite://")
+    try:
+        await upgrade(eng)
+        await downgrade(eng, "base")
+        assert await table_names(eng) == set()
+        await upgrade(eng)
+        assert await table_names(eng) == TABLES
+    finally:
+        await eng.dispose()
+
+
+INSERT_USER = text(
+    "INSERT INTO users (tg_id, full_name, role, is_active, joined_at) VALUES (:id, 'u', :role, 1, '2026-01-01')"
+)
+
+
+async def test_enum_check_rejects_garbage(engine: AsyncEngine) -> None:
+    async with engine.begin() as conn:
+        await conn.execute(INSERT_USER, {"id": 1, "role": "admin"})
+    with pytest.raises(IntegrityError):
+        async with engine.begin() as conn:
+            await conn.execute(INSERT_USER, {"id": 2, "role": "root"})
+
+
+async def test_deleting_draft_cascades_to_changes(sessions: SessionMaker) -> None:
+    async with sessions.begin() as s:
+        s.add(User(tg_id=1, full_name="a"))
+        await s.flush()
+        draft = Draft(user_id=1, base_sha="0" * 40, expires_at=utcnow() + timedelta(hours=1))
+        draft.changes.append(DraftChange(path="services/a/main.py", op=ChangeOp.ADD, content=b"print(1)"))
+        s.add(draft)
+    async with sessions.begin() as s:
+        await s.execute(text("DELETE FROM drafts"))
+    async with sessions() as s:
+        assert (await s.execute(text("SELECT count(*) FROM draft_changes"))).scalar_one() == 0