Determine value and key type

The iterable value and type can be determined based on the called methods and/or callbacks passed to those methods. Use PHPStan syntax for generics and callables.

No files or tests are named. Start by locating the iterable methods and callback declarations in the repository, then compare how their value and key types should be expressed using PHPStan generics and callable syntax. Done means the relevant types can be determined consistently from methods and callbacks.

Written by the indexing model from the issue text.