Cleaned up the frame.ts by splitting payload parsing to subpackages

test/frame.test.ts

@@ -1,7 +1,7 @@
 import { Dissected, FieldType } from "@hamradio/packet";
 import { describe, expect, it } from "vitest";
 
-import { Address, Frame, Timestamp } from "../src/frame";
+import { Address, Frame } from "../src/frame";
 import {
   DataType,
   type ITimestamp,
@@ -12,6 +12,7 @@ import {
   type PositionPayload,
   type StatusPayload
 } from "../src/frame.types";
+import Timestamp from "../src/timestamp";
 
 // Address parsing: split by method
 describe("Address.parse", () => {