Add metadata suite and relax lefthook requirement (#43)

* [auth] Add metadata suite for running metadata discovery tests

Adds a new 'metadata' suite that runs just the auth/metadata-* scenarios
for faster iteration when testing metadata discovery specifically.

Usage: node dist/index.mjs client --suite metadata --command "..."

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

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

* Don't require lefthook to be installed

Set assert_lefthook_installed to false so the hooks gracefully skip
if lefthook is not installed on the system.

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

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

---------

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

src/scenarios/client/auth/discovery-metadata.ts

@@ -217,3 +217,8 @@ export const AuthMetadataVar3Scenario = createMetadataScenario(
 
 // Export all scenarios as an array for convenience
 export const metadataScenarios = SCENARIO_CONFIGS.map(createMetadataScenario);
+
+// Export function to list metadata scenario names (for suite support)
+export function listMetadataScenarios(): string[] {
+  return metadataScenarios.map((s) => s.name);
+}