feat(v4.0.0): five nodes from nothing -- Hera asks for nodes, births and joins them

MESH.md step 5, in the fabric under test; the products are still one
node each until steps 8 and 9.

manage.c: what Hera asks of whoever holds the fabric, eleven requests by
KERNEL-WORD -- NODE-ME -BORN -WIRE -UNWIRE -SLEEP -WAKE -KILL -PARITY and
CAPSULE-OPEN -CELL -LINE. Nucleus: PORT!, SEND-ON, AWAIT, (SEAL).
capsules/v4/hera.4th: BIRTH and UNIT, the unit rule in FORTH and nowhere
else. The dictionary hash moves to the engine (v4_image_dict_hash).

test_host_unit.c, 34 checks, 64-bit: Hera is born empty, takes the
nucleus through her port, FORTH-79, POST and her capsule; 10 UNIT; four
nodes are born, each takes the nucleus and FORTH-79 through its port from
Hera and passes POST 538/538; four parities, one dictionary hash; they
talk, and a message between two corners not wired goes by Hera.

All v4 tests at both widths and under ASan+UBSan. hosted-check on three
ISAs. Bare metal: logs/20261006-143934 (amd64), -144204 (aarch64),
-144601 (riscv64).

Open, recorded in MESH.md: not run at 32 bits; a node that never answers
leaves Hera waiting; the capsules are read from files in the test, not
from the baked directory.

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

v4/README.md

@@ -123,6 +123,15 @@ read -- or, of two neighbours, the one with the lower number may wait.
 `NEIGHBOUR ( node port -- )` tells a node who is on each port. A node with
 no room for one more message lets it go and counts it in `(LOST)`.
 
+**Five nodes from nothing** (`MESH.md` step 5) is built and proven in the
+fabric under test: Hera asks whoever holds the fabric for a node
+(`v4/src/manage.c`: `NODE-BORN`, `NODE-WIRE` and the rest), sends it the
+nucleus through the port that joins them, then FORTH-79 and POST a line at
+a time, and joins four such nodes in a square round her
+(`capsules/v4/hera.4th`: `BIRTH`, `UNIT`). `v4/tests/test_host_unit.c`.
+The two products are not yet this: they become the five nodes at steps 8
+and 9.
+
 **This is still the lone node.** On bare metal `kernel_main.c` starts it
 before the fleet tables, beside the kernel's own system and not in the VM's
 place. `ENGINE.md` sets out the steps from here; step 1 is done and step 2 is