[ahmed7p]

Description

This PR fixes an issue where declaring duplicate static fields (or a mix of static and instance fields with the same name) during script parsing did not throw an error.

Changed

• Before: Having multiple static fields or a static field and an instance field with the same name inside a script class would silently pass without throwing any parse error.
• Now: Any duplicate field declaration (whether static or instance) is caught immediately during parse time (Parser.hx) and throws a proper parser error.

Key Changes

• Added duplicate name validation in Parser.hx.
• Cleaned up the redundant runtime check in PolymodScriptClass.hx.