Fix duplicate builder members when constructor parameter matches property

[WojciechNagorski]

Summary

• fix duplicate generated members when a constructor parameter and property represent the same logical member (case-insensitive match, e.g. type and Type)
• ensure property metadata is used when de-duplicating so _isSet and assignment logic stay correct
• generate primary-constructor invocation parameters directly from constructor symbols

Tests

• add regression DTO for constructor-parameter/property name collision
• add generator test to verify no duplicate _type field or WithType overloads are emitted and builder behavior remains correct

Fixes #76

[StefH]

@WojciechNagorski
I think you forgot to checkin a file?
See build error...

[StefH]

Can you also fix the unit tests?