Add FormatterBuilder for fluent formatter chaining

[henriquemoody]

The FormatterBuilder provides a fluent API to chain multiple formatters together, making it simpler to compose complex string transformations. Instead of manually instantiating and nesting formatters, developers can now use a readable builder pattern.

Assisted-by: Claude Code (Claude Opus 4.5)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.27%. Comparing base (0e4e571) to head (99829b7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main       #3      +/-   ##
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+ Coverage     99.22%   99.27%   +0.04%     
- Complexity      126      132       +6     
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  Files            11       12       +1     
  Lines           259      276      +17     
============================================
+ Hits            257      274      +17     
  Misses            2        2              

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[Copilot]

Pull request overview

This pull request introduces a FormatterBuilder to support fluent chaining of existing formatters (MaskFormatter, PatternFormatter, PlaceholderFormatter), along with integration tests and documentation updates. It also adds mixin interfaces to improve the static analysis story around fluent builder usage.

Changes:

• Added FormatterBuilder, which composes multiple Formatter instances and uses __call/__callStatic with reflection to dynamically instantiate formatter classes based on method names.
• Introduced integration tests for FormatterBuilder, a TestingFormatter helper, and a dedicated PHPUnit testsuite for integration tests.
• Updated the README with a usage example demonstrating chained formatter operations via FormatterBuilder.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/FormatterBuilder.php	Implements the fluent builder that chains Formatter instances, including dynamic formatter resolution, error handling, and static factory support.
src/Mixin/Chain.php	Defines a Chain mixin interface extending Formatter with static methods returning FormatterBuilder to describe the fluent chaining API.
src/Mixin/Builder.php	Defines a Builder mixin interface describing static factory-style builder entry points (mask, pattern, placeholder) for static analysis.
tests/Integration/FormatterBuilderTest.php	Adds integration tests that verify single and multiple formatter chains, static factory calls, and key exception paths for FormatterBuilder.
tests/Helper/TestingFormatter.php	Provides a simple Formatter implementation for tests that captures input and returns a deterministic or generated output.
phpunit.xml.dist	Registers a new integration testsuite to run the integration tests under tests/Integration/.
README.md	Documents the new fluent builder usage pattern with a concrete example combining mask and pattern formatters.

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[alganet]

General questions for now. I want to understand better some decisions. Is the defensiveness in the __call preparation for something later?