Builder interface methods should be static to support static analysis

[henriquemoody]

Problem

The Builder mixin interface defines all methods as instance methods, but it's intended to help static analysis tools discover static method calls on FormatterBuilder.

Current Behavior

Methods in src/Mixin/Builder.php are declared as:

public function area(string $unit): FormatterBuilder;

But when using the builder, methods are called statically:

FormatterBuilder::area('m²')

Expected Behavior

Methods in Builder should be declared as public static to match the actual usage pattern and help static analysis tools correctly identify these methods:

public static function area(string $unit): FormatterBuilder;

Difference Between Builder and Chain Mixins

• Builder mix: Should enable static method calls on FormatterBuilder (e.g., FormatterBuilder::area())
• Chain mix: Enables chaining instance methods after a builder is created (e.g., $builder->area()->lowercase())

Impact

Static analysis tools (PHPStan, Psalm, IDE autocomplete) cannot discover or validate static method calls on FormatterBuilder because the interface declares them as instance methods.