mem: rename Allocator primitives to alloc_bytes/dealloc_bytes (Phase 4 naming pulled forward, Agra-approved)

examples/1322-ffi-objc-arc-00-allocator-thread.sx

@@ -7,7 +7,7 @@
 //   2. The state struct's first field is `__sx_allocator` (captures the
 //      tracker so -dealloc can free through it).
 //   3. `f.release()` drives refcount → 0 → -dealloc fires → reads the
-//      captured allocator → calls tracker.dealloc(state).
+//      captured allocator → calls tracker.dealloc_bytes(state).
 //   4. The alloc/dealloc deltas around the call pair balance to (+1, +1)
 //      — exactly one sx-defined-class state struct round-trips.
 //