chore: support Python 3.14 (requires-python ">=3.11, <3.15")

Raise the upper Python bound to include 3.14 and the lower bound to 3.11.

The scipy/numpy releases that ship Python 3.14 wheels (scipy >=1.16,
numpy >=2.3) dropped Python 3.10 wheels, so no single universal-lock
version can cover both 3.10 and 3.14. scipy 1.17.x / numpy 2.4.x ship
wheels for 3.11 through 3.14, so 3.11-3.14 are supported together while
3.10 is dropped.

- Regenerate pdm.lock for the new range (scipy 1.17.1, numpy 2.4.6).
- Ignore the pdm-generated .python-version file.

Verified: pdm install and the full unit suite (482 passed) on Python 3.14.3.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: philipph-askui

.gitignore

@@ -85,7 +85,7 @@ ipython_config.py
 # pyenv
 #   For a library or package, you might want to ignore these files since the code is
 #   intended to run in multiple environments; otherwise, check them in:
-# .python-version
+.python-version
 
 # pipenv
 #   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.