✏ README, fix start-once bug and refactor

- Added some configuration and running to README
- Refactored some code
- Fixed exception when stopping a start-once script
- Only allow running with pnpm
- Moved transactions into sparebank1Api.ts
- Formatted

config.ts

@@ -22,6 +22,7 @@ export const BANK_ACCOUNT_IDS = getArrayOrThrow("BANK_ACCOUNT_IDS")
 export const DB_FILENAME = getOrDefault("DB_FILENAME", "default")
 export const LOG_LEVEL = getOrDefault("LOG_LEVEL", "info")
 
+// Utility functions
 function getOrDefault(key: string, def: string): string {
   return process.env[key] || def
 }