Launch Copilot coding agent from Sentry Root Cause Analysis

### Value Prop

When Sentry pinpoints the root cause of an error, you shouldn’t have to stop and switch tools to get it fixed. This feature lets you launch the Copilot coding agent straight from Sentry Root Cause Analysis (Seer), automatically carrying over the right context so you can go from insight to action in a single click.

### Expected Outcome

Faster fixes with less friction. Instead of copying stack traces, hunting down the right files, and re-explaining the problem in GitHub, you can generate a strong first pass at the code change immediately and move straight into review. The result: shorter time-to-fix for Sentry issues, smoother on-call and triage workflows, and more time spent shipping improvements, not stitching together context across tools.

此路线图 issue 未指出任何文件、测试或入口点，因此请先定位 Sentry Root Cause Analysis 和 GitHub Copilot coding agent 的集成点。完成的标准是用户可以从 Seer 一键启动 coding agent，并将相关上下文传递到 GitHub。

由索引模型根据 Issue 内容生成。