Support PySAM on Python 3.14 via nlr-pysam package

[mokazemi]

Changes

• Updates optional dependency from nrel-pysam to nlr-pysam
• Uncomment nlr-pysam in Python 3.14 CI requirements
• PySAM 8.0.0+ is distributed as nlr-pysam for Python 3.8-3.14

Testing

The existing test test_fit_cec_sam shows minor numerical differences when using nlr-pysam 8.0.0+:

• Adjust parameter: 2.3 → 1.507 (~34% difference)
• Other parameters within 5% tolerance

This may indicate algorithmic improvements or changes in nlr-pysam and should be reviewed by maintainers familiar with the PySAM library.

Closes #2871

• Closes Support PySAM on Python 3.14 via the nlr-pysam package name #2871
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• Tests added
• Updates entries in docs/sphinx/source/reference for API changes.
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[github-actions]

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