feat: deprecate boolean typedef in favor of bool

[Aymane-ST]

Summary

Deprecate the legacy boolean typedef in favor of standard C++ bool, while keeping it available for backward compatibility.

Why

boolean is a historical Arduino alias. In modern C++, bool is the standard and preferred type.

Marking boolean as deprecated:

• preserves compatibility,
• keeps old code building,
• encourages gradual migration

Compatibility

This is a non-breaking change:

• boolean remains available,
• it is still an alias of bool,
• existing code should continue to compile,
• users may now see a deprecation warning when using boolean.

Ref: #242

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.53%. Comparing base (cd91833) to head (af606a0).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #265   +/-   ##
=======================================
  Coverage   95.53%   95.53%           
=======================================
  Files          16       16           
  Lines        1076     1076           
=======================================
  Hits         1028     1028           
  Misses         48       48           

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[per1234]

Thanks for your pull requests @Aymane-ST! I will close this as a duplicate of the prior #242.

It is true that this PR is slightly higher quality in that it does not contain the out of scope trailing whitespace trimming present in #242. However, those changes are minimal, and beneficial in their own right, and no maintainer requested their removal. So I don't think the presence of those out of scope changes justifies superseding #242 with this PR.