Add FormatterModifier to unify placeholder modifiers

[henriquemoody]

Introduce a generic FormatterModifier that dynamically instantiates and applies any formatter based on the pipe syntax. This eliminates the need to create separate modifier classes for each formatter.

The modifier parses {{placeholder|formatterName:arg1:arg2}} syntax, resolves the formatter class via FormatterBuilder, and applies it to the value. If the formatter doesn't exist or fails, it gracefully delegates to the next modifier in the chain.

Assisted-by: Copilot
Assisted-by: OpenCode (ollama-cloud/glm-4.7)
Assisted-by: Claude Code (Claude Opus 4.5)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.47%. Comparing base (801a389) to head (3a9d71c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #12      +/-   ##
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+ Coverage     99.45%   99.47%   +0.01%     
- Complexity      155      163       +8     
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  Files            23       24       +1     
  Lines           368      382      +14     
============================================
+ Hits            366      380      +14     
  Misses            2        2              

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[Copilot]

Pull request overview

This PR introduces FormatterModifier, enabling any existing formatter (e.g. date, number, mask, pattern, metric) to be used directly in PlaceholderFormatter pipe syntax, reducing the need for formatter-specific modifier classes. It also updates placeholder parsing to better support backslash-escaped characters in modifier arguments and expands docs/tests accordingly.

Changes:

• Add FormatterModifier and prepend it to PlaceholderFormatter’s default modifier chain.
• Update placeholder parsing regex to support backslash-escaped sequences within the pipe segment.
• Add unit/integration tests and documentation for using formatters as modifiers (including escaped : / | in arguments).

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/PlaceholderFormatter.php	Prepends FormatterModifier to the default modifier chain; updates placeholder regex for escaped sequences.
src/Modifiers/FormatterModifier.php	New modifier that resolves formatters dynamically via FormatterBuilder and applies them based on pipe syntax.
tests/Unit/PlaceholderFormatterTest.php	Adds coverage for escaped : and `
tests/Unit/Modifiers/FormatterModifierTest.php	Adds unit tests for formatter resolution/delegation behavior.
tests/Integration/PlaceholderFormatterWithFormattersTest.php	Adds integration tests demonstrating formatters used as modifiers in templates.
docs/modifiers/Modifiers.md	Adds FormatterModifier to the list of available modifiers.
docs/modifiers/FormatterModifier.md	New documentation describing syntax, escaping, and behavior of FormatterModifier.
docs/PlaceholderFormatter.md	Updates docs to show formatter-as-modifier usage and links to FormatterModifier docs.
README.md	Adds a quick-start example for using formatters as modifiers.
composer.lock	Adds lockfile to the repository.

Comments suppressed due to low confidence (1)

docs/modifiers/FormatterModifier.md:176

• The “Value Conversion” and “Error Handling” sections describe delegating to the next modifier to stringify non-strings and delegating when a formatter throws during formatting. The current implementation casts scalar values to string directly and does not catch exceptions from format(). Please align the documentation with the actual behavior, or update the implementation to match the documented delegation behavior.

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