feat(v4.0.0): every message begins through the wait -- a stuck node holds up no one

(GATE) offers a message's first word and sleeps until it is taken, taking
in whatever is written to the node meanwhile; (PAY) offers every refusal
owed at once, one to a port; a node that owes one sleeps in the wait.
Writing without looking, looking again and again, and the lower-number
rule are gone.  Text from the console for a node whose own text waits to
begin a message ends that text Interrupted.  The lone node's hosts serve
an offer as a write.  MESH.md 7c; plan step 6d task 2.

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

v4/tests/test_host_quit.c

@@ -213,6 +213,7 @@ static int run_line(long max)
     while (steps < max && idle < 64) {
         (void)v4_exec_step_word(&n, &es, &h);
         steps++;
+        (void)v4_node_offer_as_write(&n);                               /* in the wait: what it offers is a write, the kernel and the console taking at once */
         if (n.asking && n.ask_port == 0) { kernel_serve(); v4_node_port_served(&n); continue; }   /* a request */
         if (n.asking && n.ask_port == CONSOLE_PORT) {                   /* a word of a message from the node */
             v4_cell word = n.request;