feat: workspace profile pictures, drag-to-reorder, and quick-switch sidebar

[Rhino47]

Pre-flight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.

Description of Change

Adds three quality-of-life improvements to the workspace system:

• Workspace profile pictures — pick any image per workspace, stored locally in userData/workspaceIcons/. Falls back to first-letter initials. No server sync required, works in accountless mode.
• Drag-to-reorder workspaces — native HTML5 drag and drop in the drawer, order persisted to the local server.
• Quick-switch sidebar — slim icon bar sits next to the service sidebar when the drawer is closed. One click to switch workspaces without opening the drawer.

Motivation and Context

Previous attempts at workspace icons (#1240) and reorder (#497) both stalled on server sync complexity. This implementation removes that blocker entirely — icons are local files, order uses the existing order column already in the schema. 13 files changed, no new dependencies, no schema migrations required.

Screenshots

A working Windows build is available to test at:
https://github.com/Rhino47/ferdium-app/releases/tag/v7.1.3-rhino.1

Checklist

• My pull request is properly named
• I tested/previewed my changes locally

Release Notes

feat: add workspace profile pictures, drag-to-reorder, and quick-switch sidebar — built by @Rhino47 / Mister Rhino

[Rhino47]

Bugs found. working on it

[mreizinho]

Love the new features but please allow the quick switch bar to have the option to show/hide or auto hide.

[Rhino47]

@mreizinho
Update — I rebuilt this and fixed the bugs from my earlier attempt. Also, added the show/hide option you mentioned (Settings ->Appearance -> workspace quick switch rail).
You can now choose Working build here:
https://github.com/Rhino47/ferdium-app/releases/tag/v7.1.3-workspaces-mod

⚠️ Windows 64-bit only (personal build — I only have a Windows machine to test on); full source is on my fork if anyone wants to build it for other platforms or review the code.

[mreizinho]

Loved the new rounded corner squares button layout and the outline on the selected workspace!

Some feedback:

• Right click no longer works on the quick-switch rail. You have to open the workspace drawer to actually edit a workspace.
• Auto-hide doesn't work for me. I thought that it was because I'm using dual display with two monitors. Tested with just one and it still doesn't work.
• Please add the shortcut keys to the tooltip after the name of the workspace (Ctrl+Alt+1), (Ctrl+Alt+2), etc.
• Drag-to-reorder workspaces also doesn't work ON THE quick-switch rail. But it works on the workspace drawer.