[ENHANCEMENT] Migrate static analysis away from phan

[codemasher]

Describe the feature

This (and all other chillerlan libraries) use phan/phan as static analysis tool.
The problem is, that both, the phan library as well as its required extension php-ast seem unmaintained for several months now (or even abandoned). On top of that, several of phan's dependencies emit deprecation notices in PHP 8.4, so this migration is crucial for PHP 8.4+.

The 2 popular options here are phpstan and psalm. I don't have an opinion yet, but I'd prefer the one that gives me the least of a headache.

Update: It has been decided on phpstan.
Update2: It seems that phan isn't entirely dead - let's see how it develops. Would be great to have it alongside as it's the only static analyzer that properly takes care of imports.

Are you (the requester) willing to submit a pull request for that feature?

[YES] (I guess!?)