fix: update ImpersonationBanner tests to match current component API

- Import ImpersonationSession from @groombook/types (component was updated in #78)
- Remove stale tests: "shows customer name" and "returns null when inactive"
  (component no longer renders customer name or checks session.active)
- Add isExtended prop to all render calls (component now takes isExtended as prop)
- Fix "does not show Extend button when already extended" to pass isExtended={true}
  instead of session.extended (prop was extracted from session in #78)
- Fix clients.test.ts: selectRows typed as Record<string,unknown>[] to allow
  spread in returning() callbacks (resolves TS2698)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/__tests__/clients.test.ts

@@ -26,7 +26,7 @@ const DISABLED_CLIENT = {
 
 // ─── Queue-based mock DB ──────────────────────────────────────────────────────
 
-let selectRows: unknown[] = [];
+let selectRows: Record<string, unknown>[] = [];
 let insertedValues: Record<string, unknown>[] = [];
 let updatedValues: Record<string, unknown>[] = [];
 let deletedId: string | null = null;