revert(v4.0.0): step 6d, the wait, is backed out -- two reviews found it unsound

Ruled 2026-10-08.  The engine, the nucleus and their tests are as they
were at dfabfa46, before step 6d; the code of the wait and its tests are
in history at 075385ab..2cf37aab.  The limit of MESH.md 7b.7 stands: a
node that is stuck can hold up its neighbours until Hera kills it.

MESH.md 7c is kept as the record of the design as approved, and 7c.6 says
what was built, what the two reviews found, the cause the findings share
-- a node's message machinery runs on the stacks its text is using, and a
fault abandons whatever was in progress -- and what a second attempt
must settle before anything is built.

Kept from it, in hosted-check: a line that leaves 29 values on the stack,
and WORDS with 26 values on it.  Both hung the products at some commit of
the wait.

make -C v4 test and sanitize at both widths, hosted-check, lint; three
bare-metal boots typing both.  POST 538 of 538, word_count=317,
dict_hash=0xc0769523a47b7dc3 on all six: the hash of step 6c's code.

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

v4/system/boot.c

@@ -107,7 +107,6 @@ static int run_line(const v4_boot *b, const char *text, unsigned len, char *keep
     for (;;) {
         (void)v4_exec_step_word(n, b->es, b->h);
         if (n->stopped) return V4_BOOT_LINE_STOPPED;
-        (void)v4_node_offer_as_write(n);                       /* in the wait (MESH.md 7c): what it offers is a write, here where whatever is on a port takes at once */
 
         if (n->asking && n->ask_port == KERNEL_PORT) {         /* a request: the kernel's turn */
             if (v4_blocks_serve(&boot_blocks, n, n->request)) {       /* a block, as for any node */