Bug report

Describe the bug

The recent refactor introduced a missing type safety and potential runtime error:

remove_ctx and add_ctx lacked documentation, making their purpose unclear.
get_send_file_max_age returned a value without proper type casting, triggering type: ignore comments.
The static file route used a lambda referencing a weakref; if the app was garbage‑collected it could raise an obscure error.
raise_routing_exception raised request.routing_exception without guaranteeing it was not None, leading to a possible TypeError.

These issues manifested as type‑checking failures and potential crashes when serving static files or handling routing exceptions.

Steps to reproduce

Run the test suite (pytest).
Observe type: ignore warnings and potential failures in test_regression.py when static files are accessed.
Manually trigger a routing exception (e.g., abort with a redirect) and notice that raise_routing_exception may raise None.
Access a static file after the app has been garbage‑collected (unlikely in normal use but possible in long‑running processes).

Expected behavior

Functions should have clear docstrings.
get_send_file_max_age should return an int or None with proper type casting.
The static file view should raise a clear RuntimeError if the app is unavailable.
raise_routing_exception should assert the exception exists before raising.

Environment

This issue was created automatically using the repository's issue template.