feat: add new themes and improve UI components

- Introduced multiple new themes: retro, dracula, nord, monokai, tokyonight, solarized, gruvbox, catppuccin, onedark, and synthwave.
- Updated global CSS to support new themes and added custom variants for theme-specific styles.
- Enhanced layout and sidebar components with improved styling and responsiveness.
- Refactored button and slider components for better visual consistency and added an animated outline variant.
- Improved various views (e.g., settings, welcome, context) with updated styles and better user experience.

This update enhances the overall aesthetic and usability of the application, providing users with more customization options.

app/src/components/views/interview-view.tsx

@@ -357,7 +357,7 @@ export function InterviewView() {
       data-testid="interview-view"
     >
       {/* Header */}
-      <div className="flex items-center justify-between p-4 border-b border-white/10 bg-zinc-950/50 backdrop-blur-md">
+      <div className="flex items-center justify-between p-4 border-b border-border bg-glass backdrop-blur-md">
         <div className="flex items-center gap-3">
           <Button
             variant="ghost"
@@ -545,7 +545,7 @@ export function InterviewView() {
                   <Button
                     onClick={handleCreateProject}
                     disabled={!projectName || !projectPath || isGenerating}
-                    className="w-full bg-gradient-to-r from-brand-500 to-purple-600 hover:from-brand-600 hover:to-purple-700 text-white border-0"
+                    className="w-full bg-linear-to-r from-brand-500 to-brand-600 hover:from-brand-600 hover:to-brand-600 text-primary-foreground border-0"
                     data-testid="interview-create-project"
                   >
                     {isGenerating ? (