T1: restructure to domain/application/infrastructure + schema version 1

- Move cashflow_model/ -> domain/
- Move engine/ -> application/
- Move cli/, sync/, ai/ -> infrastructure/
- Update all imports across codebase and tests
- Add version=1 to FinancialModel.to_dict() with migration hook in from_dict
- Update pyproject.toml: cf entry point and packages.find

Tests: 63/63 pass.

domain/model.py

@@ -0,0 +1,78 @@
+import json
+from dataclasses import dataclass, field
+from pathlib import Path
+
+from domain.account import Account
+from domain.asset import Asset
+from domain.currency import DEFAULT_RATES, ExchangeRate
+from domain.liability import Liability
+from domain.recurring import RecurringCashflow
+from domain.scenario import ForecastScenario
+from domain.transaction import Transaction
+
+
+@dataclass
+class FinancialModel:
+    base_currency: str = "RUB"
+    accounts: list[Account] = field(default_factory=list)
+    transactions: list[Transaction] = field(default_factory=list)
+    recurring: list[RecurringCashflow] = field(default_factory=list)
+    assets: list[Asset] = field(default_factory=list)
+    liabilities: list[Liability] = field(default_factory=list)
+    scenarios: list[ForecastScenario] = field(default_factory=list)
+    exchange_rates: list[ExchangeRate] = field(default_factory=lambda: DEFAULT_RATES.copy())
+
+    SCHEMA_VERSION = 1
+
+    def to_dict(self) -> dict:
+        return {
+            "version": self.SCHEMA_VERSION,
+            "base_currency": self.base_currency,
+            "accounts": [a.to_dict() for a in self.accounts],
+            "transactions": [t.to_dict() for t in self.transactions],
+            "recurring": [r.to_dict() for r in self.recurring],
+            "assets": [a.to_dict() for a in self.assets],
+            "liabilities": [li.to_dict() for li in self.liabilities],
+            "scenarios": [s.to_dict() for s in self.scenarios],
+            "exchange_rates": [r.to_dict() for r in self.exchange_rates],
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "FinancialModel":
+        version = data.get("version", 0)
+        if version == 0:
+            return cls._from_v0(data)
+        if version == 1:
+            return cls._from_v1(data)
+        raise ValueError(f"Unsupported FinancialModel version: {version}")
+
+    @classmethod
+    def _from_v1(cls, data: dict) -> "FinancialModel":
+        return cls(
+            base_currency=data.get("base_currency", "RUB"),
+            accounts=[Account.from_dict(a) for a in data.get("accounts", [])],
+            transactions=[Transaction.from_dict(t) for t in data.get("transactions", [])],
+            recurring=[RecurringCashflow.from_dict(r) for r in data.get("recurring", [])],
+            assets=[Asset.from_dict(a) for a in data.get("assets", [])],
+            liabilities=[Liability.from_dict(li) for li in data.get("liabilities", [])],
+            scenarios=[ForecastScenario.from_dict(s) for s in data.get("scenarios", [])],
+            exchange_rates=[ExchangeRate.from_dict(r) for r in data.get("exchange_rates", [])],
+        )
+
+    @classmethod
+    def _from_v0(cls, data: dict) -> "FinancialModel":
+        # Legacy: файлы, сохранённые до введения version. Совпадает по структуре с v1.
+        return cls._from_v1(data)
+
+    def save(self, path: str | Path) -> None:
+        path = Path(path)
+        path.parent.mkdir(parents=True, exist_ok=True)
+        with open(path, "w", encoding="utf-8") as f:
+            json.dump(self.to_dict(), f, indent=2, ensure_ascii=False)
+
+    @classmethod
+    def load(cls, path: str | Path) -> "FinancialModel":
+        path = Path(path)
+        with open(path, "r", encoding="utf-8") as f:
+            data = json.load(f)
+        return cls.from_dict(data)