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/system/post_cases.c

@@ -877,7 +877,7 @@ const v4_post_case v4_post_cases[] = {
     { "-TRAILING.empty", l318, 1u, V4_POST_STACK, 0, 0u, "\012", 1u },
     { "CMOVE.basic", l319, 2u, V4_POST_STACK, 0, 0u, "65 66 \012", 7u },
     { "CMOVE.empty", l320, 1u, V4_POST_STACK, 0, 0u, "", 0u },
-    { ">IN.initial", l321, 1u, V4_POST_STACK, 0, 0u, "9 \012", 3u },
+    { ">IN.initial", l321, 1u, V4_POST_STACK, 0, 0u, "6 \012", 3u },
     { ">IN.advances", l322, 1u, V4_POST_STACK, 0, 0u, "0 \012", 3u },
     { "..positive", l323, 1u, V4_POST_STACK, 0, 0u, "42 \012", 4u },
     { "..negative", l324, 1u, V4_POST_STACK, 0, 0u, "-42 \012", 5u },