Redesign builder navbar and desktop sidebars to match dashboard/overlay UI language

[Copilot]

The builder chrome (top navbar + sidebars) looked visually inconsistent with the rest of the product, especially compared to the dashboard and builder overlays (command palette, keyboard shortcuts, context menu). This update aligns those surfaces to a single cinematic design system while keeping all existing editor behavior unchanged.

• Scope: visual redesign only (no logic/path changes)

  • Reworked builder navbar and both desktop sidebars for consistent tone, depth, and spacing.
  • Preserved existing actions, shortcuts, toggles, resizing behavior, and panel content.

• Navbar refresh

  • Upgraded header shell to layered glass/gradient treatment with amber accent rails.
  • Standardized toolbar icon button states (default/hover/active/disabled/danger) to match overlay components.
  • Improved hierarchy with subtle branding tag and refined separators.
  • Increased mobile icon button hit area for better touch ergonomics.

• Sidebar shell refresh (left + right)

  • Replaced flat panel treatment with gradient/glass shells and stronger edge definition.
  • Added ambient accent lines and depth so sidebars feel integrated with command-surface styling.
  • Updated resize-handle affordances to remain visible while fitting the new visual language.

• Shared sidebar layout alignment

  • Updated SidebarLayout header/body framing to the same palette and contrast model used by overlays.
  • Kept content structure and scrolling behavior intact.

Example of the chrome style shift in the builder shell:

<header
  className="h-14 shrink-0 flex items-center gap-2 px-3 z-30 relative"
  style={{
    background: 'linear-gradient(180deg, rgba(14,13,11,0.95) 0%, rgba(9,8,7,0.95) 100%)',
    borderBottom: '1px solid rgba(196,124,46,0.14)',
    backdropFilter: 'blur(20px) saturate(1.25)',
  }}
>