[Fix] Modal-like sidebar layout on mobile screens

[waqas2714]

What changed

The sidebar now behaves like a modal on small screens to improve usability on mobile devices.

Details

• The sidebar is toggled off by default on mobile screen sizes.
• It can be opened using the Inspect button, which toggles the sidebar.
• Additional toggle buttons are added to the headers of the feature list and entity editor, allowing mobile users to easily navigate back to the map view.

Closes #11739
Relates to #9815

Screenshots

Testing

• Tested locally with npm start
• Verified behavior using browser mobile emulation
• Confirmed desktop layout remains unchanged

Checklist

• Tested locally
• No unrelated changes