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/MemoryDuckDBData.ts

@@ -0,0 +1,32 @@
+import { DuckDBType } from '@duckdb/data-types';
+import { DuckDBValue } from '@duckdb/data-values';
+import { DuckDBData } from './DuckDBData.js';
+
+export class MemoryDuckDBData extends DuckDBData {
+  constructor(
+    private columns: { name: string; type: DuckDBType }[],
+    private values: DuckDBValue[][],
+  ) {
+    super();
+  }
+
+  get columnCount() {
+    return this.columns.length;
+  }
+
+  get rowCount() {
+    return this.values.length > 0 ? this.values[0].length : 0;
+  }
+
+  columnName(columnIndex: number): string {
+    return this.columns[columnIndex].name;
+  }
+
+  columnType(columnIndex: number): DuckDBType {
+    return this.columns[columnIndex].type;
+  }
+
+  value(columnIndex: number, rowIndex: number): DuckDBValue {
+    return this.values[columnIndex][rowIndex];
+  }
+}