fix(logging): handle mid-line streaming output in test logger and add streaming tests

test/tstest/test.gap-debug.ts

@@ -0,0 +1,12 @@
+import { tap, expect } from '../../ts_tapbundle/index.js';
+
+tap.test('check for gaps in streaming', async () => {
+  // This should print "ABCD" with no gaps
+  process.stdout.write("A");
+  process.stdout.write("B");
+  process.stdout.write("C");
+  process.stdout.write("D\n");
+  expect(true).toEqual(true);
+});
+
+export default tap.start();