Add Component Showcase and development preview page

- Introduce `ComponentShowcase` to display all design system components (buttons, cards, alerts, etc.) for development and testing purposes.
- Create a dedicated `/dev/components` route for accessing the showcase.
- Ensure reuse of existing `shadcn/ui` components with appropriate styling.
- Update `PasswordResetConfirmForm` to use `bg-muted` for the password strength indicator background.

frontend/src/components/auth/PasswordResetConfirmForm.tsx

@@ -223,7 +223,7 @@ export function PasswordResetConfirmForm({
           {/* Password Strength Indicator */}
           {watchPassword && (
             <div className="space-y-2" id="password-requirements">
-              <div className="h-2 bg-gray-200 dark:bg-gray-700 rounded-full overflow-hidden">
+              <div className="h-2 bg-muted/30 rounded-full overflow-hidden">
                 <div
                   className={`h-full transition-all ${
                     passwordStrength.strength === 100