Travel_Ledger_Engine

Manages the financial + operational ledger for the Travel Architect suite. Creates and maintains Trip objects (UUID), appends immutable LedgerEntries for all lifecycle changes (hold/confirm/ticket/refund/fees), performs currency-aware spend vs budget with FX lookup, tracks supplier costs/commissions/margins, produces BalanceSnapshot summaries for dashboards/simulations, enforces financial policies (e.g., HARD_BLOCK when over budget), and ensures auditability by linking entries to segments and providers (Duffel/Amadeus/Skyscanner/etc.).