updateTransactionCategory bound the JS boolean `true`. tauri-plugin-sql
passes a bool to sqlx as a JSON value, so the column received the TEXT
'true', which the getting-started checklist's `is_manually_categorized = 1`
never matches: step 5 never ticked.
toSqlFlag turns a boolean, a number or a backup's string into 0/1. It is
used when a category is set by hand and when a JSON or CSV backup is
restored, since a backup exported while the bug stood carries "true"
(the CSV path read it as 0).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
