feat(v4.0.0): POST is the kernel's -- the boot feeds the cases, and nothing of the harness is on the node

The boot runs POST with the runner (v4/system/post.c) after the capsules:
it feeds the 538 cases to the node and judges them from outside.  A
case's printing no longer reaches the console.  What the cases define
stays in the dictionary, as in v3; the system is sealed after POST and
the boot prints PARITY:V4_SYSTEM word_count=N dict_hash=..., as v3 prints
its parity after POST.

Gone: capsules/v4/post79.4th and its blocks 7000 up; the harness words;
(CATCH) and (EMIT-HOOK), with what EMIT and the prompt loop did for them.

The generator runs v3 on the lines as the kernel sends them, without the
capsule's "T| ".  One expected result follows from that: >IN.initial
prints 6, not 9.

make -C v4 test, sanitize and hosted-check pass; amd64, aarch64 and
riscv64 boot, POST 538 of 538, word_count=411, dict_hash
0x6fb1d09418b189ee on all six: logs/20261007-105118, -105335, -105651.
T{ is unknown at the prompt; RS1 prints 42 42 before and after COLD.  A
scratch build with one expectation changed names the case and ends
PARITY:FAIL, POST: FAILED.

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

v4/capsule/core.v4

@@ -251,18 +251,12 @@ header CMOVE
   (OUT) (OUT^) a! ! ;
   NONE: drop ;
 
-\ EMIT puts the character with what has been printed, unless (EMIT-HOOK)
-\ holds the xt of a word: then that word is given it instead ( c -- ), and
-\ returns to EMIT's caller.  Everything the node prints goes through EMIT,
-\ so a hook sees all of it.  The hook is taken off when the text being
-\ interpreted ends (quit.v4), so that nothing can leave a node silent.
-\ POST uses it to compare what a case prints (docs/v4.0.0/NUCLEUS.md 6.3).
-\ A is kept: the words that print have always been free to use it across
-\ an EMIT.  As v3, only the low 8 bits of the character are printed.
+\ EMIT puts the character with what has been printed.  Everything the node
+\ prints goes through EMIT.  A is kept: the words that print have always
+\ been free to use it across an EMIT.  As v3, only the low 8 bits of the
+\ character are printed.
 header EMIT
 : EMIT ( c -- )
-  (EMIT-HOOK) b! @b  if NONE  push ;
-  NONE: drop
   255 and  a push  push                  \ A, and then the character, to the return stack
   (OUT^) b! @b a!  pop !+  a !b          \ the character goes where (OUT^) points, which moves on
   a (OUT)+256 xor if FULL  drop  pop a! ;

v4/capsule/quit.v4

@@ -48,18 +48,10 @@ macro R-CLEAR   RSTACK-DEPTH b! a !b   endmacro
 \ structures.  A definition that was under way stays hidden.
 : (RESET)   0 STATE a! !  (CG-RESET)  CFBASE (CFP) a! ! ;
 
-\ CATCHING A LINE'S ERROR.  While the variable (CATCH) is not zero, a line
-\ that ends in an error -- a fault, or a code in NODE-ERROR -- does not say
-\ ERROR: (CATCH) is set to -1 and the line is reported as completed.  Whatever message the
-\ error printed has gone wherever EMIT was sending it.  POST uses this to
-\ go on to its next case, and to check the cases that must fail
-\ (docs/v4.0.0/NUCLEUS.md 6.3).  (EMIT-HOOK), core.v4, is set to 0 here at
-\ the end of every line, caught or not.
-\
 \ ( s -- )   the text is done with.  What it printed is sent, then a message
 \ saying how it ended -- 0 QUIT, 1 completed, 2 an error -- and the node waits
-\ for the next.  (DONE) is entered with the same number and decides whether
-\ an error was one to catch; it is always jumped to, never called, by
+\ for the next.  (DONE) is entered with the same number and, for an error,
+\ stops compiling first; it is always jumped to, never called, by
 \ something that has emptied the return stack (or by a fault, which empties
 \ it).  (LINE-STATUS) keeps how the last text ended.
 : (FINISH) ( s -- )
@@ -70,11 +62,8 @@ macro R-CLEAR   RSTACK-DEPTH b! a !b   endmacro
   jump (IDLE)
 
 : (DONE)
-  (EMIT-HOOK) b! 0 !b                                                 \ what is printed is printed again
   if GO  -1 + if OK
-      drop  (RESET)
-      (CATCH) b! @b if LOUD  drop  -1 !b  1 jump (DONE)               \ caught: the text completed
-      LOUD: drop  2 jump (FINISH)
+      drop  (RESET)  2 jump (FINISH)
   OK: drop  1 jump (FINISH)
   GO: drop  0 jump (FINISH)
 
@@ -247,13 +236,11 @@ header (SEAL)
 \ further, the message for the code is printed (-1: the word has printed
 \ its own) and the line ends with ERROR.  The codes are listed in core.v4.
 header NODE-ERROR inline    : NODE-ERROR'   NODE-ERROR ;
-header (CATCH) inline       : (CATCH)'      (CATCH) ;
 header (ME) inline           : (ME)'       (ME) ;
 header (CONSOLE) inline      : (CONSOLE)'  (CONSOLE) ;
 header (LOST) inline         : (LOST)'     (LOST) ;
 header (WORD-DEFINED) inline    : (WORD-DEFINED)'    (WORD-DEFINED) ;
 header (WORD-FORGOTTEN) inline  : (WORD-FORGOTTEN)'  (WORD-FORGOTTEN) ;
-header (EMIT-HOOK) inline   : (EMIT-HOOK)'  (EMIT-HOOK) ;
 
 header QUIT
 : QUIT    R-CLEAR  (RESET)  CR  0 jump (DONE)