Allow `/goal` commands to be edited with Esc like standard prompts

What feature or improvement would you like to see?

Treat /goal commands like standard prompts in the input history/editor so they can be edited with <Esc>. Users should not need to invoke a separate /goal edit command just to revise a goal command.

Why is this useful?

The current special handling makes goal commands feel inconsistent with other prompts and adds an extra command to remember. Allowing the normal <Esc> editing flow would make it easy to correct or refine a goal in place while preserving the standard prompt interaction model.

Proposed behavior

• Pressing <Esc> on a /goal command opens it for editing just like a standard prompt.
• The edited command can be submitted normally.
• A separate /goal edit command is not required for this workflow.