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/jsonFromDuckDBValue.ts

@@ -0,0 +1,16 @@
+import { DuckDBValue } from '../DuckDBValue.js';
+import { Json } from '../Json.js';
+import { SpecialDuckDBValue } from '../SpecialDuckDBValue.js';
+
+export function jsonFromDuckDBValue(value: DuckDBValue): Json {
+  if (value === null) {
+    return null;
+  }
+  if (typeof value === 'bigint') {
+    return String(value);
+  }
+  if (value instanceof SpecialDuckDBValue) {
+    return value.toJson();
+  }
+  return value;
+}