Stage C-b: compudynamic switch decision, idle point, timer path removed (FABRIC-3.8 §3.13.3-§3.13.5)

Who runs next is now sk_vm_switch_decide(): among participants with work
(pending kernel-Hermes mail, parked mid-task, or Hera with console input),
the coolest by VM-physics heat; ties with the incumbent keep the incumbent,
ties among candidates go to the longest waiting (unique wait stamps). No
scheduler state, no timer: heartbeat_tick() no longer touches switching,
readiness/threshold/has_work/take_pending removed. Decided at owned word
checkpoints (colon words and, new, between top-level words) after a beat
or new mail, at the trampoline between messages, and at Hera's idle point
in the console poll loops. The idle pump skips participants (G3 closed for
them): the WIREBIND relay is delivered by a real switch to rajames~user.

Probe (restored away): relay via switch Hera->rajames~user->Hera on all
three ISAs, parked saved_sp inside own stack, walk-order disagreements 0
over tens of millions of decisions, 0 bytes idle log growth. Acceptance:
dict_hash unchanged, relay 3, no faults. Rulings: C-3, C-5 as proposed;
C-4 taken as (alpha), consequence recorded.

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

include/starkernel/vm/kernel_hermes.h

@@ -165,6 +165,10 @@ typedef struct {
     uint32_t orig_type;
     int      in_use;
     VMUuid   owner; /* VM whose reservoir funded this message (task 2.7) */
+    uint64_t wait_stamp; /* FABRIC-3.8.md §3.13.3 (Stage C-b): unique
+                          * admission stamp (sk_vm_switch_signal_next_stamp())
+                          * -- how long the recipient has been waiting,
+                          * for the switch decision's tie-break */
 } SkHermesMessage;
 
 /*