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/DuckDBStructValue.ts

@@ -0,0 +1,33 @@
+import { displayStringForDuckDBValue } from './conversion/displayStringForDuckDBValue.js';
+import { jsonFromDuckDBValue } from './conversion/jsonFromDuckDBValue.js';
+import { DuckDBStructEntry } from './DuckDBStructEntry.js';
+import { Json } from './Json.js';
+import { SpecialDuckDBValue } from './SpecialDuckDBValue.js';
+
+export class DuckDBStructValue extends SpecialDuckDBValue {
+  public readonly entries: readonly DuckDBStructEntry[];
+
+  constructor(entries: readonly DuckDBStructEntry[]) {
+    super();
+    this.entries = entries;
+  }
+
+  public toDuckDBString(): string {
+    const entryStrings = this.entries.map(
+      ({ key, value }) =>
+        `${displayStringForDuckDBValue(key)}: ${displayStringForDuckDBValue(
+          value,
+        )}`,
+    );
+    return `{${entryStrings.join(', ')}}`;
+  }
+
+  public toJson(): Json {
+    const result: Json = {};
+    for (const { key, value } of this.entries) {
+      const keyString = displayStringForDuckDBValue(key);
+      result[keyString] = jsonFromDuckDBValue(value);
+    }
+    return result;
+  }
+}