server/conat/api: include project_id in system.test response

For project-scoped API keys, the hub endpoint's system.test() method
was only returning account_id (empty string), making it impossible for
callers to distinguish project-scoped keys from invalid keys.

Now the method accepts and returns both account_id and project_id
depending on the key scope. This allows the Python cocalc-api client
to properly identify key scope during discovery, matching the behavior
of the project endpoint's system.test() implementation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: haraldschilly

src/packages/server/conat/api/system.ts

@@ -20,13 +20,24 @@ export function ping() {
 
 export async function test({
   account_id,
-}: { account_id?: string } = {}) {
+  project_id,
+}: { account_id?: string; project_id?: string } = {}) {
   // Return API key scope information and server time
-  // The authFirst decorator determines the scope from the API key and injects account_id.
-  const response: { account_id: string; server_time: number } = {
-    account_id: account_id ?? "",
+  // The authFirst decorator determines the scope from the API key and injects either
+  // account_id (for account-scoped keys) or project_id (for project-scoped keys).
+  const response: {
+    account_id?: string;
+    project_id?: string;
+    server_time: number;
+  } = {
     server_time: Date.now(),
   };
+  if (account_id) {
+    response.account_id = account_id;
+  }
+  if (project_id) {
+    response.project_id = project_id;
+  }
   return response;
 }