feat(v4.0.0): a node finds the way -- routes, passing on, SEND; one fault stands

MESH.md step 4. Each node has a table of destinations and the port toward
each, and a port for everything else (ROUTE, DEFAULT-ROUTE, NO-ROUTES). A
message not for this node is passed on whole; one with nowhere to go is
dropped and counted. What text prints and how it ended go back to the node
it came from by the same table. SEND sends text to another node.

test_host_mesh.c: three StarForth nodes in a row behind a console, 28
checks at both widths and under ASan+UBSan. hosted-check on three ISAs.
Bare metal: logs/20261006-115225 (amd64), -115501 (aarch64), -115849
(riscv64).

NOT DONE. Two neighbours that write to each other at once wait for ever:
a write blocks until the neighbour reads, and a node that is writing is
not reading. The last check in test_host_mesh.c shows it (KNOWN FAULT).
MESH.md section 7a sets out the ways out; none is chosen.

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

capsules/BLOCK_MAP.md

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+<!-- Generated by mkcapsule --manifest  2026-10-06T15:58:11Z -->
 <!-- DO NOT EDIT — re-run mkcapsule --manifest to refresh.  -->
 <!-- Hand-written justifications and immutability notes live  -->
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