refactor(types): centralize type definitions in shared types file

Move all interface and type definitions to src/types/index.ts to reduce code duplication and improve maintainability. This includes types for components, blog posts, personal info, and localization.

src/layouts/AboutLayout.astro

@@ -1,17 +1,11 @@
 ---
 import type { MarkdownLayoutProps } from 'astro';
-import { type Lang } from '@/i18n/utils';
+import { type Lang, type FrontmatterProps } from '@/types';
 import { defaultLang } from '@/i18n/ui';
 import GlassHeader from '@/components/GlassHeader';
 import Footer from '@/components/Footer';
 import "../styles/global.css";
 
-// Define the frontmatter structure
-interface FrontmatterProps {
-  title: string;
-  description?: string;
-}
-
 // Use Astro's MarkdownLayoutProps for proper type safety
 export type Props = MarkdownLayoutProps<FrontmatterProps>;