[FR] Hover mouse to show/hide sidebar

### Description

Similar to Notion, where the sidebar automatically appears when you move the cursor close to the edge of the screen.

https://github.com/user-attachments/assets/72d3154a-7e58-4388-9ded-8fd185c7621b

### Impact

This allows users to easily hide or show the sidebar without obstructing their view. It’s a more intuitive approach compared to repeatedly pressing a button to toggle the sidebar.

### Additional Context

It can be made optional.

The issue names no files, tests, or entry points. Start by locating the sidebar implementation and its existing toggle behavior, then review how the app detects pointer movement near the screen edge. Done means the sidebar can appear and hide on hover, with an optional setting, without obstructing the workspace.

Written by the indexing model from the issue text.