Distinguish rate limits for same-named class methods

[ghdtjdwn]

Rate-limit registration and lookup currently identify endpoints using their module and __name__, so methods such as First.index and Second.index share configuration. This can apply limits twice or allow one route's exemption to bypass another route's limit.

Use __qualname__ consistently for registration, lookup, exemptions, and middleware matching. Add regression tests for synchronous and asynchronous endpoints, static and dynamic limits, both key styles, exemptions, and default limits.

With key_style="endpoint", class methods and nested functions receive new storage keys, so existing counters are not carried over. Module-level functions and URL-based keys keep their existing keys. This behavior is documented in the examples.

Validation on Python 3.11 using the existing lock file: all 18 regression cases fail before the fix and pass afterward; all 121 tests pass after the fix. Black, mypy, and flake8 F401 pass. Documentation builds with MkDocs strict in a separate environment using compatible Markdown/importlib-metadata versions; the lock-file documentation environment fails during import on Python 3.11.

Fixes #173.

[ghdtjdwn]

The Python package workflow is waiting for approval. Could a maintainer approve the run and review the qualified route-name change for #173 when convenient? The PR description includes the regression coverage and the compatibility note about endpoint-based storage keys for class methods and nested functions.