Add --suite option to client command for running tests in parallel (#42)

Adds a --suite option to the client command that runs groups of related
tests concurrently and outputs a summary. Currently supports the 'auth' suite.

Usage: client --suite auth --command "tsx examples/clients/typescript/auth-test.ts"

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

Co-authored-by: Claude <noreply@anthropic.com>

src/scenarios/index.ts

@@ -147,3 +147,7 @@ export function listClientScenarios(): string[] {
 export function listActiveClientScenarios(): string[] {
   return activeClientScenariosList.map((scenario) => scenario.name);
 }
+
+export function listAuthScenarios(): string[] {
+  return authScenariosList.map((scenario) => scenario.name);
+}