Google Workspace Add-on for One-Click Fake Email Bounces (Desktop & Mobile Gmail)

I am seeking an experienced Google Apps Script developer to create a custom Google Workspace Add-on that enables users to trigger a realistic "Fake Email Bounce" response directly within Gmail. The add-on must work seamlessly across both Desktop Gmail (Web) and the Gmail Mobile App (iOS/Android).

Key Requirements:
- Develop using Google Apps Script (V8 Engine) with JavaScript (ES6+).
- Utilize Google Workspace CardService API for responsive UI across platforms.
- Implement Gmail API/Advanced Gmail Service for email metadata handling, MIME message creation, and cleanup actions.
- Ensure compatibility with a custom Google Workspace domain.
- Configure OAuth 2.0 scopes and manage deployment via GCP and clasp tools.

Project Completion Checklist:
- Multi-Platform Support: Add-on functions on both Desktop Gmail web interface and Gmail Mobile App (iOS/Android).
- Google Workspace Compatibility: Configured for seamless deployment within a custom Google Workspace domain.
- One-Click Trigger: Accessible directly from the Gmail action panel when viewing an email.
- Authentic Bounce Template: Non-Delivery Report (NDR) reply includes standard MTA headers and failure codes (e.g., 550 5.1.1 User Unknown / Mailbox Unavailable).
- Correct Recipient Routing: Automatically extracts and sends the bounce message to the original sender or Reply-To address.
- Automated Cleanup: Automatically moves the original email thread to Trash or Archives upon execution.
- Guided Onboarding: Full source code delivered alongside a short video or live screen-share walkthrough showing how to install and authorize it within Google Workspace.

Ideal Skills and Experience:
- Expertise in Google Apps Script, Gmail API, and JavaScript.
- Proficiency in building Google Workspace Add-ons using CardService API.
- Deep understanding of SMTP error responses, MIME structures, and header handling.
- Experience deploying internal custom add-ons for Google Workspace domains.