Increase PHPStan level to 6

[dbellettini]

This is the highest level before everything stops working (still figuring out why)

[Copilot]

Pull Request Overview

This PR increases the PHPStan static analysis level from 5 to 6, which requires more strict type annotations and removes type inference for certain scenarios. The changes primarily focus on adding proper type hints, parameter and return type annotations, and detailed PHPDoc comments throughout the codebase to satisfy the stricter analysis requirements.

Key changes include:

• Added comprehensive type annotations to method parameters and return types
• Enhanced PHPDoc comments with detailed array shapes and generic types
• Fixed type-related issues identified by the higher PHPStan level
• Added proper type assertions and null checks for better type safety

Reviewed Changes

Copilot reviewed 71 out of 71 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
phpstan.neon	Updated PHPStan level from 5 to 6 and added configuration for stricter analysis
Multiple test files	Added type hints to closures, method parameters, and enhanced PHPDoc annotations
Multiple source files	Added comprehensive type annotations, return types, and detailed array shape documentation
src/Recruiter/functions.php	Enhanced array_group_by function with proper generics and type safety
src/Recruiter/Infrastructure/Command/OptionTools.php	New utility trait for type-safe option handling

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