Improve performance of Prefix transformer

[alganet]

The Prefix transformer had many loops that could be avoided. This change replaces them for a compiled PCRE regex, taking advantage of recent PCRE JIT capabilities introduced in PHP.

These changes offer no performance trade-offs, improving lookup for all categories of prefixes (property/key with shift, ignore list and fallback to simple rule).

The most affected is the simple rule (no prefix or no conflict with any kind of prefix rule), yielding the most gains.

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Gains by scenario:

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.53%. Comparing base (b352f17) to head (4ab2bdc).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1665      +/-   ##
============================================
+ Coverage     99.29%   99.53%   +0.23%     
  Complexity      920      920              
============================================
  Files           190      190              
  Lines          2141     2148       +7     
============================================
+ Hits           2126     2138      +12     
+ Misses           15       10       -5     

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[Copilot]

Pull request overview

This PR optimizes the Prefix transformer by replacing multiple string-prefix loops with a single cached PCRE regex match, and adds PhpBench benchmarks to measure the impact.

Changes:

• Reworked Respect\Validation\Transformers\Prefix to use a cached preg_match()-based parser.
• Replaced linear skip-list checks with isset() lookups on associative arrays.
• Added PhpBench benchmarks for common Prefix transformer scenarios.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/Transformers/Prefix.php	Replaces prefix detection loops with a cached regex-based match and reorganizes rule lists for faster lookups.
tests/benchmark/PrefixBench.php	Adds benchmark scenarios to evaluate Prefix::transform() performance across common inputs.

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