feat(testing): configure ignored routes in test server

[hugosmoreira]

Summary

• add an optional TestServerOptions bag to getTestServer
• pass ignoredRoutes through while preserving the existing default behavior
• document and test disabling the default favicon and robots.txt short-circuit

Fixes #778

Validation

• TypeScript compilation
• 7 focused HTTP integration tests
• 108 repository tests, including the pack-and-install smoke test
• ESLint and Prettier on the changed TypeScript files
• API Extractor
• git diff --check