Validate untyped hash and CLI fixture values

The packaged xxHash export has no resolved type declaration. Check the
factory, engine, and bigint result at the benchmark boundary, and treat
CLI fixture rejection values as unknown.

Add regression cases for invalid engines and hash results while retaining
the real-engine and initialisation-count assertions.

src/apps/cli/test-support/p2p-automatic-host.test.ts

@@ -82,7 +82,7 @@ export async function runP2PAutomaticHostFixture(options: CLIOptions, context: C
     }
     const commandOutcome = runCommand(options, context).then(
         (result) => ({ type: "result" as const, result }),
-        (error) => ({ type: "error" as const, error })
+        (error: unknown) => ({ type: "error" as const, error })
     );
     const connectedWaitStarted = Date.now();
     while (!service.transportLifecycle.isConnected) {