Add SVG assets and TypeScript configuration

- Created a new SVG for the Open Graph image (og-image.svg) with a gradient background and text elements.
- Added Vercel logo SVG (vercel.svg) for deployment branding.
- Introduced a window icon SVG (window.svg) for UI representation.
- Initialized TypeScript configuration file (tsconfig.json) with strict settings and module resolution for a React project.

app/components/MarkdownPreview.tsx

@@ -0,0 +1,26 @@
+"use client";
+
+import { useMemo } from "react";
+import { marked } from "marked";
+
+interface MarkdownPreviewProps {
+  content: string;
+}
+
+export default function MarkdownPreview({ content }: MarkdownPreviewProps) {
+  const html = useMemo(() => {
+    if (!content) return '<p class="preview-empty">Commencez à écrire pour voir l\'aperçu...</p>';
+    try {
+      return marked.parse(content, { breaks: true, gfm: true }) as string;
+    } catch {
+      return content;
+    }
+  }, [content]);
+
+  return (
+    <div
+      className="markdown-preview prose"
+      dangerouslySetInnerHTML={{ __html: html }}
+    />
+  );
+}