[UI] Implement sidebar with layer controls

[newtontech]

Task: Layer Control Sidebar

Priority: MEDIUM
Module: UI Components

Description

Create sidebar component for controlling visualization layers.

Tasks

• Collapsible sidebar component
• Layer visibility toggles (atoms, bonds, unit cell)
• Display style selector (ball-stick, space-fill, wireframe)
• Material controls (opacity, shininess)

Acceptance Criteria

• Toggle atom visibility
• Switch between display styles
• Settings persist during session