[feat] Movable Interface Panels

[charlypa]

Describe the problem

https://discord.com/channels/879126209114542181/961981994059841556/1347679782036574289

In the current Phoenix Code editor, the main interface panels (file browser, problems panel, live preview, etc.) are fixed in predefined locations:

• File browser is locked to the left side
• Live preview is locked to the right side
• Problems panel and other tool panels appear in fixed positions
• Output/terminal panels are locked to the bottom

This rigid panel arrangement limits workflow customization, as users cannot:

• Move the file browser to the right if preferred
• Position the live preview on the left or bottom
• Rearrange tool panels based on their importance to the current task
• Create custom layouts that better suit their specific development needs or monitor setup

While Phoenix Code does support split views for editor content, the structural UI panels themselves remain locked in place.

Describe the solution you'd like

Implement a flexible panel system that allows:

• Draggable structural panels - Make all main UI panels (file browser, problems, live preview, terminal, etc.) draggable to any docking position
• Panel relocation options - Allow panels to be moved to any edge (top, bottom, left, right)
• Tab grouping - Permit panels to be grouped together as tabs within the same container space
• Context menu for panel management - Right-click option to move/relocate panels
• Panel layout memory - Remember custom panel arrangements between sessions
• Panel visibility toggles - Quick shortcuts to show/hide panels without losing their position

This enhancement would significantly improve workspace customization while preserving the editor's clean design, allowing developers to adapt the interface to their specific workflows rather than adapting their workflows to the interface.

Alternatives considered

No response

Additional context

No response