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

examples/0809-memory-xx-lvalue-borrows.sx

@@ -17,8 +17,8 @@ main :: () -> s32 {
     // xx tracker — operand is an identifier (lvalue), so the protocol
     // borrows tracker's storage. No heap copy. Mutations propagate.
     push Context.{ allocator = xx tracker, data = null } {
-        p := context.allocator.alloc(128);
-        context.allocator.dealloc(p);
+        p := context.allocator.alloc_bytes(128);
+        context.allocator.dealloc_bytes(p);
     }
 
     print("alloc_count   = {}\n", tracker.alloc_count);