feat(blog) add CMS, render blog posts list

- use GitHub repo as cms, read idx.json
- blog posts list

app/public/type/Result.ts

@@ -0,0 +1,7 @@
+export type Result<T, E> = {
+    ok: true;
+    value: T;
+} | {
+    ok: false;
+    error: E;
+};