Provide for deletion of remote agent sessions.

[4kbyte]

Describe the feature or problem you'd like to solve

The /resume menu can delete local sessions but refuses to delete remote without any remedy.

Proposed solution

Either enable deletion so that /resume can delete both local and remote, or provide a tip for how the user can remedy, either some gh command or a URL to visit.

Example prompts or workflows

No response

Additional context

[GitHub Copilot v1.0.40]

There is currently no way to delete a remote Copilot coding agent session:

• In the CLI, /resume lists Local and Remote sessions together. x keypress deletes local sessions but works for local rows but says "Cannot delete remote sessions from here." for remote.
• On the web, https://github.com/copilot/agents and https://github.com/copilot/tasks only offer Stop and Archive — no delete action in any menu.
• gh has no command for managing these sessions.

Net result: every remote agent run accumulates in account history forever, with no user-facing remedy.

This is a real problem in everyday use:

1. Experimentation noise. Iterating on prompts or kicking off speculative agent runs quickly produces dozens of throwaway sessions. Archive-only means the dashboard accumulates clutter that can never be cleaned up.
2. Privacy / hygiene. Sessions can contain prompts, file contents, and reasoning traces that users may legitimately want to remove (mistaken inputs, sensitive paths, abandoned exploration). "Archive" is not a substitute for delete.
3. Asymmetry with the rest of GitHub. Issues, PRs, branches, gists, and even local Copilot CLI sessions can all be deleted by their owner. Remote agent sessions are the odd one out.

Example: https://github.com/copilot/tasks/86e2c4dd-723a-4f53-90c5-d7c6c46b7fc7 — I want this gone, and there is no surface that will let me do it.