Function cleanupGoogleSheets

cleanupGoogleSheets(sheetId: string): Promise<void>
Cleans up Google Sheets by removing last month's transactions from the specified sheets. This function performs the following operations:
1. Fetches existing data from the specified sheets (expenses, incomes, investments).
2. Filters out transactions from the last month.
3. Writes the filtered data back to the respective sheets.
Parameters
- sheetId: string
  Google Spreadsheet ID where the sheets are located.
Returns Promise<void>
Promise Resolves when cleanup is completed.

Throws
Error If an error occurs during cleanup.
- Defined in src/features/googleSheetService.ts:211