fix: add unified ledger amount and enforce manual decimal precision

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

app/repositories/portfolio_repository.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 from datetime import datetime
+from decimal import Decimal
 from typing import Protocol
 
 from app.domain.models import Asset, AuthToken, BrokerCredential, Daemon, LedgerEntry, Portfolio, PortfolioComment, PortfolioTag, StrategySet, Tag, TokenPrincipal, User
@@ -320,11 +321,11 @@ class PortfolioRepository(Protocol):
         portfolio_id: str,
         *,
         action: str,
-        amount: float | None = None,
-        quantity: float | None = None,
-        price: float | None = None,
-        fee: float = 0.0,
-        tax: float = 0.0,
+        amount: Decimal | None = None,
+        quantity: Decimal | None = None,
+        price: Decimal | None = None,
+        fee: Decimal = Decimal("0"),
+        tax: Decimal = Decimal("0"),
         executed_at: datetime | None = None,
         target_ledger_entry_id: int | None = None,
         note: str = "",