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-data-values/test/DuckDBDateValue.test.ts

@@ -0,0 +1,18 @@
+import { expect, suite, test } from 'vitest';
+import { DuckDBDateValue } from '../src/DuckDBDateValue';
+
+suite('DuckDBDateValue', () => {
+  test('should render a normal date value to the correct string', () => {
+    expect(new DuckDBDateValue(19643).toString()).toStrictEqual('2023-10-13');
+  });
+  test('should render the max date value to the correct string', () => {
+    expect(new DuckDBDateValue(2 ** 31 - 2).toString()).toStrictEqual(
+      '5881580-07-10',
+    );
+  });
+  test('should render the min date value to the correct string', () => {
+    expect(new DuckDBDateValue(-(2 ** 31) + 2).toString()).toStrictEqual(
+      '5877642-06-25 (BC)',
+    );
+  });
+});