host: polish — a third fold domain (deps) + a live execute-fold demo (/workflow-demo)

Two concrete demonstrations of the composition architecture:

THIRD DOMAIN (proves step 8's "a new domain is just a dict + leaf, no new control flow").
host/comp-deps folds a composition to the object ids it TRANSCLUDES — the static contains
DAG of a body. It reuses host/comp-fold's seq/alt/each dispatch verbatim; only the leaf
(collect `(ref ID)`) + accumulator (concat) are new. Useful in its own right (what a
(seq (ref c0) (each … (ref …))) body pulls in; context-specific — alt picks the taken
branch). compose suite 20/20.

LIVE EXECUTE-FOLD DEMO (makes step 7 tangible, parallel to /compose-demo for render).
/workflow-demo runs ONE composition object's :body through host/exec-run — the SAME structure
the render-fold would turn into HTML, folded by execute into a plan of effects (validate →
branch on status → notify each recipient). host/blog-seed-workflow-demo! + host/blog-workflow-
demo + route + serve.sh seed. Shows the behaviour model IS an execute-fold over a composition
object — the same object the block editor authors. blog suite 165/165.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/host/serve.sh

@@ -159,6 +159,11 @@ EPOCH=1
   echo "(epoch $EPOCH)"
   echo "(eval \"(host/blog-seed-compose-demo!)\")"
   EPOCH=$((EPOCH+1))
+  # Seed the EXECUTE-fold demo (composition step 7): /workflow-demo runs ONE composition
+  # object through host/exec-run — the same algebra as render, folded to an effect log.
+  echo "(epoch $EPOCH)"
+  echo "(eval \"(host/blog-seed-workflow-demo!)\")"
+  EPOCH=$((EPOCH+1))
   # Load relation metadata (symmetry/labels) from the relation-posts into the
   # in-memory cache, so render paths read it without a (VmSuspending) durable read.
   echo "(epoch $EPOCH)"