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-ui-client/src/http/functions/makeDuckDBUIHttpRequestHeaders.ts

@@ -0,0 +1,39 @@
+import { toBase64 } from '../../util/functions/toBase64.js';
+
+export interface DuckDBUIHttpRequestHeaderOptions {
+  description?: string;
+  connectionName?: string;
+  databaseName?: string;
+  parameters?: unknown[];
+}
+
+export function makeDuckDBUIHttpRequestHeaders({
+  description,
+  connectionName,
+  databaseName,
+  parameters,
+}: DuckDBUIHttpRequestHeaderOptions): Headers {
+  const headers = new Headers();
+  if (description) {
+    headers.append('X-DuckDB-UI-Request-Description', description);
+  }
+  if (connectionName) {
+    headers.append('X-DuckDB-UI-Connection-Name', connectionName);
+  }
+  if (databaseName) {
+    // base64 encode the value because it can contain characters invalid in an HTTP header
+    headers.append('X-DuckDB-UI-Database-Name', toBase64(databaseName));
+  }
+  if (parameters) {
+    headers.append('X-DuckDB-UI-Parameter-Count', String(parameters.length));
+    for (let i = 0; i < parameters.length; i++) {
+      // base64 encode the value because it can contain characters invalid in an HTTP header
+      // TODO: support non-string parameters?
+      headers.append(
+        `X-DuckDB-UI-Parameter-Value-${i}`,
+        toBase64(String(parameters[i])),
+      );
+    }
+  }
+  return headers;
+}