v1.1.0 — Native Gmail API auth

What's new

• Replaced gog subprocess calls with native Gmail API integration
• Added OAuth token flow using google-auth-oauthlib
• Added Python requirements file for Gmail client dependencies
• Updated setup docs for native OAuth

Why

• Cleaner architecture (no shell-out dependency)
• Better portability for users
• Reduced security-scanner false-positive risk around subprocess execution

Migration

Existing users need one-time OAuth auth run for the new token file.