Rewrite argtyper in Go using php-parser-in-go

[TomasVotruba]

Replaces the PHP + PHPStan + Rector implementation with a self-contained Go tool built on php-parser-in-go.

What it does

argtyper add-types <path> walks the project, records the types of literal arguments passed into calls, then fills in missing parameter type declarations.

• Collects literal argument types: int, float, string, bool, array, null, and new X() as object:X.
• Resolves call targets from the syntax tree alone: new X(), X::m(), self::m(), $this->m() and plain function() calls.
• Groups types per parameter position; single type is applied, single type + null becomes nullable, multiple types are skipped as ambiguous.
• Skips params that already have a type, magic methods (except __construct), and methods that may override a parent/interface (unless private or constructor).

Scope vs the old version

The PHP tool used PHPStan's type inference, so it could type a param even when the argument was a variable carrying a known type. The Go version has no inference engine - it uses only the parsed AST, so it handles literal values passed into statically resolvable targets. Calls on arbitrary variables ($service->method(...)) are skipped, since the class cannot be resolved without inference. Classes are matched by short name.

Layout

• main.go - CLI
• internal/finder - find PHP files in code dirs
• internal/collect - record literal arg types at call sites
• internal/aggregate - resolve one type per parameter
• internal/apply - add missing param types and reprint
• internal/phpast - shared AST helpers

CI

PHP workflows replaced with a Go build workflow (gofmt, vet, build, test). Tests cover collect, aggregate, apply and finder.