mairhythmhoon/ts-mailer ? reverse-engineered prompt

Build me a TypeScript service that automates email workflows from Google Sheets.

It should read contact and event data from a spreadsheet, render nice HTML emails from templates, and send them through Gmail with OAuth. I need three jobs: one for birthday wishes and festival or custom event greetings, one for new joiner thank you emails based on records added since the last run, and one for a monthly log report that zips up the log files and emails them. It should also write delivery history, run summaries, and checkpoints back to Google Sheets so I can track what happened.

Please include local data files, reusable modules for Gmail, Sheets, calendar lookups, logging, and shared setup, plus separate templates for each email type. Make it safe to run with real accounts, so keep credentials in a private Secure folder and use clear validation and logging. If you need current Google API details or package guidance, look them up online first.