Remove all obsolete authentication, settings, admin, and demo-related components and pages

- Eliminated redundant components, pages, and layouts related to authentication (`login`, `register`, `password-reset`, etc.), user settings, admin, and demos.
- Simplified the frontend structure by removing unused dynamic imports, forms, and test code.
- Refactored configurations and metadata imports to exclude references to removed features.
- Streamlined the project for future development and improved maintainability by discarding legacy and unused code.

frontend/src/app/[locale]/dev/docs/design-system/[...slug]/page.tsx

@@ -0,0 +1,75 @@
+/**
+ * Dynamic Documentation Route
+ * Renders markdown files from docs/ directory
+ * Access: /dev/docs/design-system/01-foundations, etc.
+ */
+
+import { notFound } from 'next/navigation';
+import { promises as fs } from 'fs';
+import path from 'path';
+import matter from 'gray-matter';
+import { MarkdownContent } from '@/components/docs/MarkdownContent';
+import { DevBreadcrumbs } from '@/components/dev/DevBreadcrumbs';
+
+interface DocPageProps {
+  params: Promise<{ slug: string[] }>;
+}
+
+// Generate static params for all documentation files
+export async function generateStaticParams() {
+  const docsDir = path.join(process.cwd(), 'docs', 'design-system');
+
+  try {
+    const files = await fs.readdir(docsDir);
+    const mdFiles = files.filter((file) => file.endsWith('.md'));
+
+    return mdFiles.map((file) => ({
+      slug: [file.replace(/\.md$/, '')],
+    }));
+  } catch {
+    return [];
+  }
+}
+
+// Get markdown file content
+async function getDocContent(slug: string[]) {
+  const filePath = path.join(process.cwd(), 'docs', 'design-system', ...slug) + '.md';
+
+  try {
+    const fileContent = await fs.readFile(filePath, 'utf-8');
+    const { data, content } = matter(fileContent);
+
+    return {
+      frontmatter: data,
+      content,
+      filePath: slug.join('/'),
+    };
+  } catch {
+    return null;
+  }
+}
+
+export default async function DocPage({ params }: DocPageProps) {
+  const { slug } = await params;
+  const doc = await getDocContent(slug);
+
+  if (!doc) {
+    notFound();
+  }
+
+  // Extract title from first heading or use filename
+  const title = doc.content.match(/^#\s+(.+)$/m)?.[1] || slug[slug.length - 1];
+
+  return (
+    <div className="bg-background">
+      {/* Breadcrumbs */}
+      <DevBreadcrumbs items={[{ label: 'Documentation', href: '/dev/docs' }, { label: title }]} />
+
+      <div className="container mx-auto px-4 py-12">
+        <div className="mx-auto max-w-4xl">
+          <MarkdownContent content={doc.content} />
+        </div>
+      </div>
+    </div>
+  );
+}