Handle ASGI apps without route templates

[Mirochill]

Summary

• avoid assuming ASGI apps expose Starlette/FastAPI-style routes when resolving template paths
• fall back to the full request path for apps without route templates, such as Connexion middleware wrappers
• add regression coverage for an app object without routes

Fixes #102

Validation

• Not run locally
• Static validation only: git diff --check