fix(v4.0.0): a waiting node goes on passing on and paying; KILL is not held by a stuck node

Found in the five-node test, each with a check that failed first:
- A node with answers it could not give to two stuck senders began no
  text at all.  It now holds back only text from a sender whose own
  answer is still with it.
- KILL waited to tell a stuck node, and a typed line that broke it left
  the nodes after it untold.  GONE is put with the messages waiting, as
  how text ended is, and goes when it can.
- So that 'tell, then wait' still works, AWAIT does what (IDLE) does but
  for beginning text: it looks through the messages waiting, offers what
  is to be passed on and what is owed, and sleeps in the wait.  A waiting
  node no longer keeps back what passes through it.
- A node in the wait with an offer on a port that turns out to have
  nothing on it is woken and told so (which port: 2 * V4_PORTS + k); no
  error is raised on it.  (GATE) makes it error 18; (IDLE) and AWAIT let
  the message go.  Before, removing a node raised 'No one on that port'
  on the unrelated text of a neighbour that had something queued for it.

make -C v4 test and sanitize at both widths, hosted-check.

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

v4/capsule/core.v4

@@ -251,17 +251,20 @@ header CMOVE
 \ ( port to -- )   take in a message and keep it
 : (TAKE)   (TAKE-HDR)  jump (TAKE-KEEP)
 
-\ ( -- flag )   THE WAIT, once.  Whatever has been offered stands until
-\ this returns.  Zero: a word came for this node instead; that whole
-\ message has been taken in and kept, (TAKE), and its seven words are
-\ still in (MQ-HDR).  Not zero: an offer was taken; B is at the port it
-\ was taken on, and (GATE-PORT) holds that port's address.
+\ ( -- how )   THE WAIT, once.  Whatever has been offered stands until
+\ this returns.  0: a word came for this node instead; that whole message
+\ has been taken in and kept, (TAKE), and its seven words are still in
+\ (MQ-HDR).  -1: an offer was taken; B is at the port it was taken on, and
+\ (GATE-PORT) holds that port's address.  1: there is nothing on a port
+\ that had an offer: no one will ever take it.
 : (OFFERS)
   (WAIT) b! @b  push  (PORT)+9 b! @b                                  \ ( which )   R: the word
   dup -PORTS +  -if TAKEN
   drop  (PORT) +  dup b!  pop  (TAKE)  0 ;                            \ a word, from that port: the message's first
-  TAKEN: (PORT) +  (GATE-PORT) a! !  drop  pop drop
+  TAKEN: dup -PORTS +  -if NOONE                                      \ ( which k x )   k: the port, by its number
+         drop  (PORT) +  (GATE-PORT) a! !  drop  pop drop
          (GATE-PORT) a! @ b!  -1 ;
+  NOONE: drop drop drop  pop drop  1 ;
 
 \ ( w port -- )   BEGIN A MESSAGE: the word, its first, is offered on the
 \ port, by its address, until it is taken; whatever is written to this
@@ -274,11 +277,12 @@ header CMOVE
 \ the messages waiting and is done next.  It is how a node whose text must
 \ begin a message to a node that is stuck is typed to.  Not while (QUIET)
 \ is set: what waits then is no text's doing.
-\ With nothing on the port the fabric raises error 18.
+\ With nothing on the port it is error 18.
 : (GATE1) ( port -- )
   (GATE-PORT) a! !
   L: (GATE-WORD) a! @  (GATE-PORT) a! @  -PORTS -  4 +  a! !            \ the offer
-     (OFFERS)  if CAME  drop ;
+     (OFFERS)  if CAME  -if NOONE  drop ;
+  NOONE: drop  NODE-ERROR b! 18 !b ;                                  \ no one on that port
   CAME: drop
      (QUIET) a! @  if TEXTS  drop  jump L
   TEXTS: drop