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! ;