refactor(arap): rustfmt the unit's files, and the write-off's SOURCE line (P4b S7)

No behaviour: the files as rustfmt leaves them after the unit's edits
(the commits before this one were made before the formatter ran), and the
Ledger::write_off spec block cites A-5 alone for the direct write-off
method (A-6 is the hand-entry refusal, not this command).

crates/ledger-store/src/lib.rs

@@ -49,6 +49,6 @@ pub use snapshot::{DiskCheck, Snapshot};
 pub use store::{
     Attachment, BillPreview, DepreciationRun, DisposalPreview, EntryRow, EventRow, InvoicePreview,
     JOURNAL_FILE, LEGACY_DB_FILE, LOCK_FILE, MAX_RECURRING_RUN, PayrollLineInput, Reconciliation,
-    Statement, Store, Subject, VerifyReport, WriteOffEvidence, database_in_use, db_file, db_file_for,
-    is_database_file,
+    Statement, Store, Subject, VerifyReport, WriteOffEvidence, database_in_use, db_file,
+    db_file_for, is_database_file,
 };