Add support or remove highlighting for non-existent integer types

[Natuworkguy]

The VS Code extension currently highlights int128, int256, and int512 as valid Rux types, but these types do not exist in the Rux language.

This causes incorrect syntax highlighting and makes it look like these integer sizes are supported when they are not.

Steps to reproduce

1. Install the Rux VS Code extension.
2. Open a .rux file.
3. Write code containing:

func Main() -> int {
    let a: int128 = 0;
    let b: int256 = 0;
    let c: int512 = 0;

    return 0;
}

4. Notice that int128, int256, and int512 are highlighted like valid built-in types.

Expected behavior

The extension should only highlight integer types that are actually supported by Rux.

If these types are not planned or implemented, they should not receive built-in type highlighting.

Actual behavior

int128, int256, and int512 are highlighted despite not existing in the language.

Possible fixes

• Remove int128, int256, and int512 from the TextMate grammar/type definitions.
• Add the types to Rux if they are intended to be supported in the future.
• Add tests to ensure syntax highlighting matches the current language specification.