Feature Overview

Add the ability to toggle/collapse the left connections tree panel with fluid spring-based motion.

Requirements & Scope:

• Fluid Spring Animation: Smoothly animate sidebar width between 0 and _lastExpandedWidth using QueryaSpring (gentle/snappy spring presets) with redirectable velocity handoff and reduced motion fallback.
• Visual clipping & Layout: Use ClipRect + OverflowBox to ensure connection tree content slides gracefully off-screen without squishing or wrapping text.
• Split Handle auto-fade: Smoothly fade out QueryaSplitHandle and disable resize dragging when collapsed.
• Toggle Controls:
  • Sidebar toggle button in QueryaWindowTitleBar with tooltip (Toggle Sidebar (Cmd+B / Ctrl+B)).
  • Global keyboard shortcut: Cmd+B (macOS) / Ctrl+B (Windows/Linux).
  • Menu item in title bar menu (View / Edit -> Toggle Sidebar).
• State Persistence: Persist isSidebarVisible and lastExpandedWidth in AppSettings.