refactor(media): share fileExists

src/media-understanding/fs.ts

@@ -0,0 +1,13 @@
+import fs from "node:fs/promises";
+
+export async function fileExists(filePath?: string | null): Promise<boolean> {
+  if (!filePath) {
+    return false;
+  }
+  try {
+    await fs.stat(filePath);
+    return true;
+  } catch {
+    return false;
+  }
+}