Switch Value from a struct with type/num/obj fields to a NaN-tagged uint64_t/double union, enabling faster type checks and unboxed numbers. Refactor all macros and accessors (IS_OBJ, AS_OBJ, AS_NUM, etc.) to work with the new representation. Hoist CallFrame pointer, instruction pointer, and bytecode array into local variables inside the interpret loop, updating them on frame push/pop. Enable NAN_TAGGING define and DEBUG_GC_STRESS in common.h. Update Xcode project to use c99 standard, pedantic warnings, and treat warnings as errors. Add benchmark/fib.txt with timing comparisons showing fib benchmark within 25% of Lua.
The default garbage collection trigger threshold in newVM() is raised from 1024*1024 (1MB) to 1024*1024*10 (10MB) to reduce GC frequency for larger workloads. Additionally, the DEBUG_GC_STRESS macro in common.h is commented out to disable stress-test GC collections on every allocation by default.
Replace manual malloc/free for Obj allocations with GC-managed heap. Add Obj->next linked list, markObj traversal for all object types, and sweep phase in VM. Introduce MAX_PINNED stack for temporary GC roots during compilation. Refactor all object constructors (newBool, newFunction, newClass, newNum, newString) to accept VM pointer and register allocations. Move function constant registration earlier in compiler to ensure GC reachability. Add DEBUG_GC_STRESS and TRACE_MEMORY macros in new common.h header.
