Tests: Add JavaScript unit tests for validation and condition logic

[priethor]

What

Add JavaScript unit tests for client-side validation and conditional field visibility logic.

Why

These modules handle user-facing validation messages and field visibility—errors here directly impact form usability.

How

File	Tests	Coverage
condition-types.test.js	83	All ~40 condition types (HasValue, EqualTo, GreaterThan, LessThan, Contains, PatternMatch, etc.)
validation.test.js	42	Validator class, error management, field validation lifecycle
conditions-manager.test.js	35	Conditional visibility with AND/OR rule combinations
condition-base.test.js	25	Base acf.Condition class and registration functions

[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 31.03%. Comparing base (7551a70) to head (958c9d4).
⚠️ Report is 4 commits behind head on trunk.

Additional details and impacted files

@@             Coverage Diff              @@
##              trunk     #339      +/-   ##
============================================
+ Coverage     30.63%   31.03%   +0.39%     
  Complexity     4410     4410              
============================================
  Files           291      291              
  Lines         36918    36918              
============================================
+ Hits          11310    11457     +147     
+ Misses        25608    25461     -147     

Flag	Coverage Δ
e2e	42.91% <ø> (-0.51%)	⬇️
javascript	10.12% <ø> (+3.58%)	⬆️
phpunit	28.70% <ø> (ø)

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