feat: integrate Pi backend and Pi Web

pi-web/lib/file-dirent.ts

@@ -0,0 +1,17 @@
+import fs from "fs";
+
+type DirentType = Pick<fs.Dirent, "isDirectory" | "isFile">;
+
+export function resolveDirentIsDirectory(
+  dirent: DirentType,
+  fullPath: string,
+): boolean | null {
+  if (dirent.isDirectory()) return true;
+  if (dirent.isFile()) return false;
+
+  try {
+    return fs.statSync(fullPath).isDirectory();
+  } catch {
+    return null;
+  }
+}