#236 - TransformerTrait: document that any #suffix is accepted on transformer codes

[njoubert-cleverage]

Description

Fixes #236.

The # suffix of transformer codes (used to chain the same transformer several times, as YAML keys must be unique) was documented as numeric only (callback#1), while the unanchored regex of TransformerTrait::getCleanedTransfomerCode() actually accepted any suffix. Named suffixes are useful to describe each step, so this PR makes them official:

• document that any non-empty suffix is accepted, in the docblock and in docs/reference/traits/transformer_trait.md (with a named suffix in the example);
• anchor the regex: /^([^#]+)#.+$/. The part before the first # is used as the transformer code if it is registered, otherwise the whole code is looked up;
• add TransformerTraitTest (code cleaning, chaining the same transformer with numeric and named suffixes, empty suffix).

On main, only the 2 tests about the empty suffix fail (it was accepted by accident). PHPUnit (with coverage), PHPStan, PHP-CS-Fixer and Rector pass, and the changed files are valid PHP 8.2.

Requirements

• Documentation updates
  • Reference
  • Cookbooks
  • Changelog
• Unit tests

Breaking changes

None in practice: numeric and named suffixes keep working. Only an empty suffix (callback#), accepted by accident, now throws a MissingTransformerException.

🤖 Generated with Claude Code