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/src/conversion/displayStringForDuckDBValue.ts

@@ -0,0 +1,11 @@
+import { DuckDBValue } from '../DuckDBValue.js';
+
+export function displayStringForDuckDBValue(value: DuckDBValue): string {
+  if (value == null) {
+    return 'NULL';
+  }
+  if (typeof value === 'string') {
+    return `'${value.replace(`'`, `''`)}'`;
+  }
+  return String(value);
+}