Phase 121: Clean up lobject.h - remove duplicate definitions

Removed duplicate sections now in focused headers:
- Removed Nil, Boolean, Thread, Number sections → lobject_core.h
- Removed Prototypes section (Proto, Upvaldesc, etc.) → lproto.h
- Removed Functions section (UpVal, Closures) → lfunc.h
- Removed Tables section (Table, Node) → ltable.h

Restored essential TValue setter functions:
- Base setters: setpvalue, setfvalue, setsvalue, setuvalue, sethvalue, setthvalue, setclLvalue, setclCvalue, setgcovalue
- Stack wrappers: sethvalue2s, setthvalue2s, setsvalue2s, setclLvalue2s

Progress:
✅ Reduced lobject.h from 2027 → 434 lines (79% reduction!)
✅ Fixed redundant declaration errors
✅ Most source files compile successfully
⚠️  Some files need explicit lgc.h includes (architectural improvement)

Next: Fix remaining GC header dependencies

Author: claude