What does this implement/fix? Explain your changes.

This PHP inlines return types for number functions where this change has been confirmed to be nonbreaking i.e.:

• cant cause an error
• wont cause an error
• would already cause an error
• are private and cant affect extenders/users

Native return types provide:

• better IDE support (dont need an extra doc-block parser)
• better LLM support (less likely to get confused or lose context)
• better DX (since the error happens where it's caused and not where the correct type is expected ).
• better refactorability (since we know what parts of the codebase are "safe".

Does this close any currently open issues?

No but I Should make more for all the 3.0 breaking type changes I wanna make 🧑‍🍳