/// GC-managed typed pointer ([`gc_ptr::GcPtr<T>`]) and the [`gc_ptr::GcObject`] trait.
/// Handle scopes and persistent roots for safe GC-pointer access.
/// Heap allocator with generational memory regions.
/// Immix-style regional GC: 32 KiB blocks, 128 B line-granularity marking,
/// opportunistic evacuation, TLABs, and concurrent old-gen marking.
/// Incremental/concurrent GC: budget-based marking, concurrent sweeping,
/// idle-time collection, and GC metrics for sub-1 ms pauses.
/// Mark-Sweep-Compact collector for the old (tenured) generation.
/// Thread-local heap runtime: allocation, collection, and root management.
/// Cheney semi-space scavenger (minor GC) and write-barrier remembered set.
/// Thread-local allocation buffers (TLABs) for fast bump-pointer allocation.
/// Mark-and-trace infrastructure for garbage collection.
/// Write barrier for tracking old-generation → young-generation pointer edges.