✏ 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

package.json

@@ -4,6 +4,7 @@
   "description": "",
   "main": "index.js",
   "scripts": {
+    "preinstall": "npx only-allow pnpm",
     "start": "dotenvx run --env-file=.env.local -- node --import=tsx ./src/main.ts | pino-pretty",
     "start-once": "ONCE=true dotenvx run --env-file=.env.local -- node --import=tsx ./src/main.ts | pino-pretty",
     "test": "dotenvx run --env-file=.env.test.local -- node --experimental-vm-modules node_modules/jest/bin/jest.js | pino-pretty",