Add keyboard shortcut hints to the command palette footer

[BittuBarnwal7479]

Describe the feature

The command palette supports keyboard navigation, but the available shortcuts are not visible to users.

Currently users can navigate with:

• ↑ / ↓ to move between results
• Enter to select
• Esc to close

However, these shortcuts are not displayed anywhere in the command palette UI.

Additional information

• Would you be willing to help implement this feature?

Final checks

• Read the contribution guide.
• Check existing issues.