Init indexed file

lib/dat/types.ts

@@ -0,0 +1,16 @@
+// src/data-file/types.ts
+export interface Serializer<T> {
+  serialize(data: T): Buffer;
+  deserialize(buf: Buffer): T;
+}
+
+export interface DataEntry<T> {
+  sequence: number;
+  timestamp: bigint;
+  data: T;
+}
+
+export interface DataFileOptions<T> {
+  serializer: Serializer<T>;
+  maxEntries?: number;
+}