feat(v4.0.0): the wait in the engine -- a node offers a word and sleeps

A node stores a word to offer on any of its ports and fetches the wait: it
is blocked until a word comes for it or one of its offers is taken, and
the fabric does the handing over in one step.  The port block moves in
the nucleus's map to make room for the new addresses.  Nothing uses it
yet.  MESH.md 7c; plan step 6d task 1.

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

v4/tests/host_map.h

@@ -73,7 +73,7 @@
 #define OWED         (BUF0_W - 112)             /* those: for each, the node it is owed to and the node the refused message was for */
 #define ACL_HOOK     (BUF0_W - 6)               /* the xt of the access control recheck word, or 0 */
 #define LINE_STATUS  (BUF0_W - 9)               /* how the last line ended: 0 QUIT, 1 completed, 2 an error */
-#define PORT         (BUF0_W - 32)              /* the node's ports (node.h): V4_PORTS of them, then "any port" and "which port".  Port 0 is where its requests go. */
+#define PORT         (BUF0_W - 144)             /* the node's ports (node.h): V4_PORTS of them, then "any port", "which port", who writes, who reads, an offer for each port, and the wait: 2 * V4_PORTS + 5 cells, between the output buffer and A_FOUND.  Port 0 is where its requests go. */
 #define CONSOLE      (BUF0_W - 16)              /* the node what this one prints is sent to; 0: whoever sent the text being served */
 #define ROUTE_COUNT  (BUF0_W - 17)              /* how many entries the table of ways holds */
 #define ROUTE_DEFAULT (BUF0_W - 18)             /* the port address for a node not in the table, or 0: there is none */
@@ -124,6 +124,8 @@ typedef char host_map_ports_fit[(V4_PORTS <= 8u) ? 1 : -1];
 #endif
 /* the messages waiting are above the dictionary */
 typedef char host_map_queue_fits[(MQ_W >= DICT_END_W) ? 1 : -1];
+/* the ports, with the offers and the wait after them, end below the cells that follow */
+typedef char host_map_port_block_fits[(PORT + 2 * (v4_cell)V4_PORTS + 5 <= BUF0_W - 115) ? 1 : -1];
 
 /* How many slots, from slot 0, a branch may sit in on a node this size: those
  * whose address field reaches every word of it. */