Unlock Extension With Email OTP

I already have the zipped source of a competing browser extension that currently charges users and limits credits. I need that same functionality—booking jobs and credit handling—re-engineered so it works completely free with unlimited credits.

Here is the flow I want implemented: the first time a new user tries to book a job, the extension must prompt for a one-time passcode sent to the user’s email. When the email verification succeeds, the job can be booked. Immediately after the very first booking, the extension should lock itself until I decide to reopen it or supply an updated build.

Key deliverables
• Modified extension (packed and unpacked) running with unlimited credits and no payment gates
• Secure email-based OTP generation, delivery, and verification tied to each user account
• Automatic self-lock after the first successful job booking
• Brief setup guide so I can rebuild or deploy future versions on my side

Please work directly in the existing ZIP I will provide and keep all existing UI elements intact unless changes are required to support the new OTP flow.