Introduce VirtualStack allocator, refactor memory management to use virtual memory stacks, and update documentation.
Added VirtualStack as a new stack allocator using virtual memory, replaced Stack with VirtualStack in allocation manager and related APIs, and updated TempJobAllocator to use VirtualArena. Introduced AllocationManagerInitOpts for allocator configuration. Replaced ENABLE_COLLECTION_CHECKS with ENABLE_SAFETY_CHECKS for safety checks. Removed Result.cs and updated project files and examples. Added comprehensive README files for all major packages and improved root documentation.
BREAKING CHANGE: Stack allocator replaced by VirtualStack; TempJobAllocator and AllocationManager initialization signatures changed; Result types removed.
Introduce VirtualArena for large, thread-safe virtual memory allocation and FreeList allocator for efficient persistent allocations. Update AllocationManager to support new allocators, add cross-platform virtual memory utilities, and improve thread-safety and performance in existing allocators. Bump version to 1.5.0 and update project configuration.
BREAKING CHANGE: AllocationManager initialization now requires explicit parameters for arena and FreeList capacities. Existing allocator usage may require code changes.
