phsl / new-api

• Removed obsolete `sidebarIconColors` map and `getItemColor` util from
  SiderBar/render; all selected states now use the single CSS variable
  `--semi-color-primary` for both text and icons.
• Simplified `getLucideIcon`:
  – Added `Package` to Lucide imports.
  – Switched “models” case to `<Package />`, avoiding duplication with
    the Layers glyph.
  – Replaced per-key color logic with `iconColor` derived from the new
    uniform highlight color.
• Stripped any unused imports / dead code paths after the refactor.
• Lint passes; sidebar hover/focus behavior unchanged while visual
  consistency is improved.