QBO formats for import/export; server-side receipt enforcement policy in MCP spec

docs/architecture.md

@@ -55,7 +55,8 @@ The core is a pure domain library and stays that way.
 | Crate | Purpose | Depends on |
 |---|---|---|
 | `ledger-store` | SQLite persistence of the entry log | `ledger-core` |
-| `ledger-import` | GnuCash XML read-only import | `ledger-core` |
+| `ledger-import` | QuickBooks CSV read-only import (bank transactions, chart of accounts) | `ledger-core` |
+| `ledger-export` | Format renderers: CSV, XLSX, IIF journal entries (QuickBooks Desktop) | `ledger-core` |
 | `ledger-oracle` | Diff harness: our engine vs GnuCash on fixture books | `ledger-core`, `ledger-import` |
 | `books-app` | egui UI (native + WASM), command-driven | `ledger-core`, `ledger-store` |