Refactor routing in App component to enhance navigation and improve error handling by integrating dynamic routes and updating the NotFound route.

node_modules/@astrojs/markdown-remark/dist/frontmatter-injection.d.ts

@@ -0,0 +1,6 @@
+import type { VFileData as Data, VFile } from 'vfile';
+import type { MarkdownAstroData } from './types.js';
+export declare class InvalidAstroDataError extends TypeError {
+}
+export declare function safelyGetAstroData(vfileData: Data): MarkdownAstroData | InvalidAstroDataError;
+export declare function setVfileFrontmatter(vfile: VFile, frontmatter: Record<string, any>): void;