Add Python 3.14 testing and update static Python version to 3.14

[Copilot]

Adds Python 3.14 to CI testing matrix and updates all single-version CI jobs from 3.13 to 3.14.

Changes

• Build workflow: Added "3.14" to test matrix alongside 3.10-3.13, updated PYTHON_VERSION env var to "3.14"
• Docs workflow: Updated PYTHON_VERSION to "3.14" for documentation builds
• Pre-commit update workflow: Updated PYTHON_VERSION to "3.14"
• Conda config: Created ci/python3.14.yaml matching format of existing version configs
• Package metadata: Added Python 3.14 classifier to pyproject.toml

All CI jobs that run on a single Python version now use 3.14 (pre-commit linting, docs builds, pre-commit auto-updates).

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add python 3.14 testing</issue_title>
<issue_description>We want to add python 3.14 to the CI testing and make sure any CI that runs on only one python version uses 3.14 (instead of 3.13).</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add python 3.14 testing #165

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[xylar]

Looks good!