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/app/dev/components/page.tsx

@@ -0,0 +1,17 @@
+/**
+ * Component Showcase Page
+ * Development-only page to preview all shadcn/ui components
+ * Access: /dev/components
+ */
+
+import type { Metadata } from 'next';
+import { ComponentShowcase } from '@/components/dev/ComponentShowcase';
+
+export const metadata: Metadata = {
+  title: 'Component Showcase | Dev',
+  description: 'Preview all design system components',
+};
+
+export default function ComponentShowcasePage() {
+  return <ComponentShowcase />;
+}