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/types.ts

@@ -0,0 +1,11 @@
+export interface Note {
+  id: string;
+  title: string;
+  content: string;
+  createdAt: number;
+  updatedAt: number;
+  pinned: boolean;
+}
+
+export type SortMode = 'date' | 'alpha';
+export type Theme = 'light' | 'dark';