Introduce ContainsCount validator

[alganet]

This validator is similar to Contains, but also checks how many times the needle appears.

Additionally, the Domain validator was changed to use it instead of relying on an unserializable callback, thus, making it serializable.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.51%. Comparing base (4618996) to head (f5e22f1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1606      +/-   ##
============================================
+ Coverage     97.47%   97.51%   +0.03%     
- Complexity      993     1006      +13     
============================================
  Files           211      212       +1     
  Lines          2298     2334      +36     
============================================
+ Hits           2240     2276      +36     
  Misses           58       58              

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[alganet]

I wanted to make the $count parameter accept a wrapped validator, but I could not do it and also have template messages. I also found out some other validators don't have that, such as Between, so I decided to stop banging my head and just deliver the simpler version.

[Copilot]

Pull request overview

This pull request introduces a new ContainsCount validator that validates whether a value appears in a string or array exactly a specified number of times. The validator supports both case-insensitive (default) and identical comparisons. Additionally, the Domain validator has been updated to use ContainsCount instead of an unserializable callback, making the Domain validator serializable.

Changes:

• Added new ContainsCount validator class with support for counting occurrences in strings and arrays
• Updated Domain validator to use ContainsCount instead of a callback, making it serializable
• Added comprehensive unit and feature tests for the new validator
• Added documentation and updated cross-references

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
library/Validators/ContainsCount.php	New validator class for checking exact occurrence count of a value
library/Validators/Domain.php	Removed unserializable callback in favor of ContainsCount
library/Mixins/Chain.php	Added containsCount method signature to Chain mixin
library/Mixins/Builder.php	Added containsCount static method signature to Builder mixin
tests/unit/Validators/ContainsCountTest.php	Unit tests for valid and invalid inputs
tests/feature/Validators/ContainsCountTest.php	Feature tests for error messages
tests/benchmark/ValidatorBench.php	Added benchmark cases for ContainsCount and Domain
docs/validators/ContainsCount.md	Documentation for the new validator
docs/validators/index.md	Updated index to include ContainsCount
docs/validators/Contains.md	Added cross-reference to ContainsCount
docs/validators/ContainsAny.md	Added cross-reference to ContainsCount

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