Collapsible/Floating Left Sidebar for Reading

[houjoe0829]

Clear and concise description of the problem

The left sidebar takes up a lot of horizontal space, which makes reading articles feel cramped. It would be great to have a way to collapse it or switch it to a floating overlay so the content can use the full width.

Suggested solution

Add a toggle to collapse the sidebar and an auto‑hide “floating” mode that appears on hover or via a keyboard shortcut. Persist the last state per device and allow optional sidebar width adjustment.

Alternative

No response

Additional context

No response

Validations

• [x] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.
• [x] This issue is valid

[linear[bot]]

FOL-2698

[TonyRL]

Duplicate of #4281