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-reader/src/AsyncDuckDBDataBatchIterator.ts

@@ -0,0 +1,11 @@
+import { DuckDBData } from './DuckDBData.js';
+
+export type DuckDBDataBatchIteratorResult = IteratorResult<
+  DuckDBData,
+  DuckDBData | undefined
+>;
+
+export type AsyncDuckDBDataBatchIterator = AsyncIterator<
+  DuckDBData,
+  DuckDBData | undefined
+>;