Stage G: SEND, and two workers interleave; decision compares work heat (FABRIC-3.8 §3.8, §3.13.7)

SEND ( paddr plen name-c name-u -- ok? ): general kernel-Hermes send to a
named VM, from = calling VM, one block max (refused, not truncated), every
VM. New SK_HERMES_MSG_TYPE_SEND (30).

Ruling C-4 (beta), Captain Bob: the switch decision compares work heat --
the heat each VM pulled in by its own per-beat charges -- not absolute
heat, so Hera's structural endowment no longer makes her hottest. Before
it, the two-worker test ran serial (AAAA...BBBB); after it, byte-identical
on amd64/aarch64/riscv64:
AAABBBBBBBBAAAAAAAABBBBBAAAAABBBBBAAAAABBBBBAAAAABBBBBAAAAABBBBBAAAAABBBBBAAAABB
(40 A, 40 B, 16 runs; ordinary words only, nothing yields). Acceptance:
relay 3, idle growth 0; dict_hash set changed by the new word
(word_count 533) and identical across ISAs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

include/starkernel/capsule_vm_physics.h

@@ -111,6 +111,18 @@ void vm_physics_touch(VMUuid vm_id);
  */
 void vm_physics_charge(VMUuid vm_id);
 
+/**
+ * vm_physics_work_heat_of - Cumulative heat a VM has pulled in by working
+ *
+ * FABRIC-3.8.md §3.13.7, ruling C-4 (β), Captain Bob 2026-09-23: the sum of
+ * every transfer vm_physics_charge() actually moved INTO this VM -- heat
+ * earned by its own work, independent of any structural endowment (Hera's
+ * initial Q48_ONE). This is the quantity the switch decision compares
+ * ("coolest VM with work" = least work heat). Only grows; 0 for an unknown
+ * or dead VM.
+ */
+uint64_t vm_physics_work_heat_of(VMUuid vm_id);
+
 /**
  * vm_physics_tick - Heartbeat-gated inference pass
  *