T4: Repository pattern — ModelRepository, JsonFileRepository, ExcelRepository

- application/repositories/model_repository.py: ModelRepository Protocol
  with load(path) and save(model, path)
- infrastructure/repositories/json_file_repository.py: JsonFileRepository
  (вынесен из FinancialModel.save/load)
- infrastructure/repositories/excel_repository.py: ExcelRepository
  (бывший ExcelSync, переименован)
- FinancialModel.save/load удалены — теперь только данные
- infrastructure/sync/ удалён (ExcelSync перенесён в repositories/)
- infrastructure/cli/main.py и config.py используют JsonFileRepository +
  ExcelRepository через локальные singletons
- test_excel_sync.py переименован в test для ExcelRepository
- Новый test_repositories.py: 5 тестов для JsonFileRepository + протокол
- test_model.py: использован JsonFileRepository

Tests: 68/68 pass (было 63 + 5 новых).

tests/test_repositories.py

@@ -0,0 +1,56 @@
+from decimal import Decimal
+from pathlib import Path
+
+from domain import Account, Asset, FinancialModel, Transaction
+from application.repositories import ModelRepository
+from infrastructure.repositories import JsonFileRepository
+
+
+class TestJsonFileRepository:
+    def test_save_load_roundtrip(self, tmp_path: Path):
+        repo = JsonFileRepository()
+        model = FinancialModel(
+            accounts=[Account(name="Test", balance=Decimal("100.50"))],
+            transactions=[Transaction(amount=Decimal("33.33"), category="income")],
+        )
+        p = tmp_path / "model.json"
+        repo.save(model, p)
+        assert p.exists()
+
+        loaded = repo.load(p)
+        assert len(loaded.accounts) == 1
+        assert loaded.accounts[0].name == "Test"
+        assert loaded.accounts[0].balance == Decimal("100.50")
+        assert loaded.transactions[0].amount == Decimal("33.33")
+
+    def test_version_field_persisted(self, tmp_path: Path):
+        repo = JsonFileRepository()
+        model = FinancialModel()
+        p = tmp_path / "v.json"
+        repo.save(model, p)
+        import json
+        with open(p) as f:
+            data = json.load(f)
+        assert data["version"] == 1
+
+    def test_creates_parent_dirs(self, tmp_path: Path):
+        repo = JsonFileRepository()
+        model = FinancialModel()
+        p = tmp_path / "nested" / "dir" / "model.json"
+        repo.save(model, p)
+        assert p.exists()
+
+    def test_implements_protocol(self):
+        repo = JsonFileRepository()
+        assert isinstance(repo, ModelRepository)
+
+    def test_decimal_preserved(self, tmp_path: Path):
+        repo = JsonFileRepository()
+        model = FinancialModel(
+            assets=[Asset(name="Stocks", value=Decimal("12345.67"), growth_rate=Decimal("8.5"))]
+        )
+        p = tmp_path / "decimal.json"
+        repo.save(model, p)
+        loaded = repo.load(p)
+        assert loaded.assets[0].value == Decimal("12345.67")
+        assert loaded.assets[0].growth_rate == Decimal("8.5")