Add a shortcut to copy the resume command

[jongio]

Problem

Copying only the session ID still leaves users to rebuild the exact resume command by hand. That is easy to get wrong when Yolo Mode, agent, model, or a custom command is configured.

Proposed solution

Add a keyboard shortcut that copies the selected session's launch command to the clipboard. The command should use the same launch settings Dispatch uses when resuming the session.

Acceptance criteria

• A visible help entry documents the new shortcut.
• The shortcut copies a command for the selected session.
• Custom command, agent, model, and Yolo Mode settings are reflected in the copied command.
• Clipboard failures show the existing status error pattern.
• Unit tests cover success and error paths.