[Bug] OAuth Authorization button disabled in Firefox on Linux

Bug Description
Bug: Firefox on Linux - OAuth “Authorize” button is disabled, blocking login

Steps to reproduce:

• On Linux, open the OAuth authorization page in Firefox
• The permissions screen loads, but the “Authorize” button stays disabled
• Copying the OAuth URL and opening it manually in Firefox has the same result
• Works in Chrome on the same Linux machine, and in Chrome on Mac

Environment:

• Claude Code: native 2.1.123 (linux-x64)
• Firefox: [please add your Firefox version here]
• OS: Linux

Environment Info

• Platform: linux
• Terminal: vte-based
• Version: 2.1.123
• Feedback ID: 7630f02a-2eb3-4ff6-9dbc-1db9736901da

<img width="1367" height="1331" alt="Image" src="https://github.com/user-attachments/assets/f8111901-48f1-461b-9220-b01ddcdc32b4" />