Unify CIF parsing, category updates, and data handling

[AndrewSazonov]

This PR introduces a substantial refactor of CIF parsing, data handling, and category update logic across the codebase.

Key changes include:

• Unified CIF parsing and serialization support across Category, Parameter, SampleModel, and Experiment
• A unified category update workflow based on update_priority, with consistent propagation through Analysis, Fitter, and Calculator layers
• Migration from independent datastore usage to the new data category
• Improved handling of d-spacing calculations and free parameters
• Introduction of new data classes for powder diffraction, total scattering, and single-crystal reflection data
• Introduction of a new download-by-id data API
• CI and dependency fixes, including workarounds for pdffit2
• Refactoring of tutorials, unit tests, and integration tests to align with the updated API

[codecov]

Codecov Report

❌ Patch coverage is 85.98248% with 112 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.26%. Comparing base (17ded39) to head (139c3c4).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/easydiffraction/io/cif/serialize.py	66.66%	19 Missing and 8 partials ⚠️
...ydiffraction/sample_models/sample_model/factory.py	42.85%	13 Missing and 3 partials ⚠️
...diffraction/experiments/categories/data/factory.py	61.29%	6 Missing and 6 partials ⚠️
src/easydiffraction/experiments/experiment/base.py	68.75%	7 Missing and 3 partials ⚠️
src/easydiffraction/project/project.py	11.11%	8 Missing ⚠️
src/easydiffraction/utils/utils.py	83.67%	5 Missing and 3 partials ⚠️
.../easydiffraction/experiments/experiment/factory.py	88.00%	4 Missing and 2 partials ⚠️
...ion/experiments/categories/background/chebyshev.py	75.00%	5 Missing ⚠️
...sydiffraction/experiments/categories/data/total.py	95.57%	4 Missing and 1 partial ⚠️
...iffraction/experiments/categories/data/bragg_pd.py	98.27%	2 Missing and 1 partial ⚠️
... and 8 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #108      +/-   ##
===========================================
+ Coverage    81.31%   82.26%   +0.94%     
===========================================
  Files           89       88       -1     
  Lines         5117     5451     +334     
  Branches       412      454      +42     
===========================================
+ Hits          4161     4484     +323     
+ Misses         810      802       -8     
- Partials       146      165      +19     

Flag	Coverage Δ
functional	?
integration	69.95% <83.85%> (?)
unittests	72.44% <59.32%> (-1.26%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.