chore(util): preserve LRU cache decorator types

[paulkagiri]

Summary of Changes

Use ParamSpec to type Falcon's internal LRU cache decorator factory so wrapped callables keep their original signatures and expose cache_clear() to static type checkers.

This removes the now-unnecessary type: ignore comments around cached resolver/status helpers and adds the narrow assertions needed where the ASGI testing client converts a collected response status after the app has responded.

Related Issues

Closes #2629

Pull Request Checklist

• Applied changes to both WSGI and ASGI code paths and interfaces (where applicable).
• Added tests for changed code.
• Performed automated tests and code quality checks by running tox.
• Prefixed code comments with GitHub nick and an appropriate prefix.
• Coding style is consistent with the rest of the framework.
• Updated documentation for changed code.
  • Added docstrings for any new classes, functions, or modules.
  • Updated docstrings for any modifications to existing code.
  • Updated both WSGI and ASGI docs (where applicable).
  • Added references to new classes, functions, or modules to the relevant RST file under docs/.
  • Updated all relevant supporting documentation files under docs/.
  • A copyright notice is included at the top of any new modules (using your own name or the name of your organization).
  • Changed/added classes/methods/functions have appropriate versionadded, versionchanged, or deprecated directives.
• Changes (and possible deprecations) have towncrier news fragments under docs/_newsfragments/, with the file name format {issue_number}.{fragment_type}.rst. (Run tox -e towncrier, and inspect docs/_build/html/changes/ in the browser to ensure it renders correctly.)
• LLM output, if any, has been carefully reviewed and tested by a human developer. (See also: Use of LLMs ("AI").)

Validation performed:

• python -m mypy --strict falcon
• python -m ruff format --check falcon/util/misc.py falcon/media/handlers.py falcon/http_error.py falcon/http_status.py falcon/response.py falcon/testing/client.py
• python -m ruff check falcon/util/misc.py falcon/media/handlers.py falcon/http_error.py falcon/http_status.py falcon/response.py falcon/testing/client.py
• python -m pytest tests/test_media_handlers.py tests/test_httpstatus.py tests/test_utils.py::TestFalconUtils::test_code_to_http_status tests/test_utils.py::TestFalconUtils::test_http_status_to_code tests/asgi/test_hello_asgi.py -q
• python tools/towncrier_draft.py --dry-run
• git diff --check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (5119682) to head (90548ce).

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #2643   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           64        64           
  Lines         7985      7990    +5     
  Branches      1103      1103           
=========================================
+ Hits          7985      7990    +5     

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[vytas7]

I don't think we need newsfragments for internal improvements that are not surface to the framework's user. I'll unlink this file unless you vehemently object.

[vytas7]

Thanks, this looks good on the whole, however I'd like to make a couple of changes before merging this (commented inline).

[vytas7]

Can you please undo these unrelated changes?
Or does going via a variable somehow help with typing?

Since this is the testing client's code, we are not that concerned about performance, but it would still be good to understand why exactly we need this pattern.

[vytas7]

These protocols look good at first glance. 👍

But could you please move them to falcon/_typing.py? We are trying to colocate such definitions in that module.