add duckdb-ui-client & other ts pkgs (#10)

* add duckdb-ui-client & other ts pkgs

* workflow fixes

* fix working dir

* no sparse checkout; specify package.json path

* path to pnpm-lock.yaml

* add check & build test

* workflow step descriptions

* use comments & names

* one more naming tweak

ts/pkgs/duckdb-ui-client/test/util/functions/toBase64.test.ts

@@ -0,0 +1,11 @@
+import { expect, suite, test } from 'vitest';
+import { toBase64 } from '../../../src/util/functions/toBase64';
+
+suite('toBase64', () => {
+  test('basic', () => {
+    expect(atob(toBase64('duck'))).toBe('duck');
+  });
+  test('unicode', () => {
+    expect(atob(toBase64('🦆'))).toBe('\xF0\x9F\xA6\x86');
+  });
+});