Improve joint-fit support and add parameter-evolution plotting

[AndrewSazonov]

Improves the joint-fit workflow across analysis and experiment models, replace the old conditions category with CIF-aligned diffrn metadata, add parameter-evolution plotting and ASCII loading helpers, and document the flow with the new tutorial and related updates.

[codecov]

Codecov Report

❌ Patch coverage is 56.62651% with 108 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.36%. Comparing base (25e84b7) to head (36a6d25).
⚠️ Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/easydiffraction/display/plotting.py	8.57%	32 Missing ⚠️
src/easydiffraction/io/ascii.py	44.44%	23 Missing and 2 partials ⚠️
...easydiffraction/datablocks/experiment/item/base.py	50.00%	12 Missing ⚠️
src/easydiffraction/display/plotters/ascii.py	10.00%	9 Missing ⚠️
...datablocks/experiment/categories/diffrn/default.py	83.33%	7 Missing ⚠️
src/easydiffraction/display/plotters/plotly.py	16.66%	5 Missing ⚠️
src/easydiffraction/analysis/analysis.py	71.42%	3 Missing and 1 partial ⚠️
...diffraction/datablocks/experiment/item/bragg_pd.py	60.00%	3 Missing and 1 partial ⚠️
src/easydiffraction/project/project.py	42.85%	3 Missing and 1 partial ⚠️
src/easydiffraction/core/collection.py	70.00%	3 Missing ⚠️
... and 3 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #130      +/-   ##
===========================================
- Coverage    83.84%   82.36%   -1.49%     
===========================================
  Files          124      132       +8     
  Lines         6544     6855     +311     
  Branches       527      570      +43     
===========================================
+ Hits          5487     5646     +159     
- Misses         869     1014     +145     
- Partials       188      195       +7     

Flag	Coverage Δ
integration	68.73% <51.40%> (-1.50%)	⬇️
unittests	71.90% <51.80%> (-1.07%)	⬇️

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