organize types a bit more sanely & bump deps

types/note.d.ts

@@ -0,0 +1,19 @@
+import type { MDXRemoteSerializeResult } from "next-mdx-remote";
+
+export type NoteType = {
+  frontMatter: {
+    slug: string;
+    permalink: string;
+    date: string;
+    title: string;
+    htmlTitle?: string;
+    description?: string;
+    image?: string;
+    tags?: string[];
+    readingMins?: number;
+    noComments?: boolean;
+  };
+
+  // the final, compiled JSX by next-mdx-remote; see lib/parse-notes.ts
+  source: MDXRemoteSerializeResult;
+};