Add GitHub Copilot to Autofix coding agent handoff docs

[AndreaGriffiths11]

DESCRIBE YOUR PR

The Autofix page lists Claude Code and Cursor as supported coding agents for handoff but omits GitHub Copilot, which is supported and documented at GitHub Copilot Agent.

This PR adds GitHub Copilot to that page:

• Updates the section heading to include GitHub Copilot
• Adds a GitHub Copilot bullet to the supported coding agents list, linking to the existing setup page
• Adds provider-specific setup links for Claude Code, Cursor, and GitHub Copilot

No behavioral or product changes; documentation only.

IS YOUR CHANGE URGENT?

• None: Not urgent, can wait up to 1 week+

PRE-MERGE CHECKLIST

• Checked Vercel preview for correctness, including links
• PR was reviewed and approved by any necessary SMEs (subject matter experts)
• PR was reviewed and approved by a member of the Sentry docs team

LEGAL BOILERPLATE

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

EXTRA RESOURCES

• Sentry Docs contributor guide

[vercel]

@AndreaGriffiths11 is attempting to deploy a commit to the Sentry Team on Vercel.

A member of the Team first needs to authorize it.

[AndreaGriffiths11]

Rendered preview of this change, built locally from the branch: