fix: allow lazy/translation proxy objects as State/Event name (#632)

[fgmacedo]

Fixes #632.

Problem

Lazy translation strings (e.g. django.utils.translation.gettext_lazy) are proxy objects that are not real str instances, although castable via str(). Changes in 3.x stored a State/Event name as-is and later assumed it was a real str, so a proxy broke:

• the TransitionNotAllowed message (str.join requires real str elements) — statemachine/exceptions.py;
• str(state) — State.__str__ returned the proxy directly, raising TypeError: __str__ returned non-string.

Fix

Coerce to str at the point of use, keeping the lazy object untouched in storage. Coercing at assignment would resolve the translation at class-definition time, defeating the purpose of i18n (translation must resolve at display time, honoring the active locale).

• exceptions.py: ", ".join(str(s.name) ...) in the TransitionNotAllowed message.
• state.py: __str__ returns str(self.name); the hash uses str(self.name) for robust hashability regardless of locale.
• contrib/diagram/extract.py: coerce names to str once at the domain→model boundary, so every renderer (dot/mermaid/table) receives real str.

Docs

• Release notes entry in docs/releases/3.2.1.md.
• Note in docs/states.md that name accepts any object castable to str, resolved at display time.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (aff3977) to head (bfadcb8).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff            @@
##           develop      #636   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           52        52           
  Lines         5505      5505           
  Branches       869       869           
=========================================
  Hits          5505      5505           

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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