Preserve ledger venue provenance (#39)

* feat: preserve ledger venue provenance

* fix: satisfy ledger test lint ratchet

* fix: advance image migration inventory

app/domain/models.py

@@ -6,7 +6,7 @@ from dataclasses import dataclass, field
 from datetime import date, datetime
 from decimal import Decimal
 from enum import Enum
-from typing import Any, Protocol, runtime_checkable
+from typing import Any, Literal, Protocol, runtime_checkable
 
 
 class MarketCode(str, Enum):
@@ -181,6 +181,8 @@ class LedgerEntry:
     target_ledger_entry_id: int | None = None
     confirmation_evidence: str | None = None
     actor_user_id: str | None = None
+    execution_venue: Literal["KRX", "NXT"] | None = None
+    order_venue: Literal["KRX", "NXT", "SOR"] | None = None
     corporate_action: dict[str, Any] | None = None
 
     def __post_init__(self) -> None: