fed-sx-types Phase 1: DefineType + SubtypeOf genesis verbs

Two new DefineActivity-form genesis activity-types for host-type
federation (plans/fed-sx-host-types.md step 1):

- next/genesis/activity-types/define_type.sx — DefineType verb; schema
  accepts an :object with a string :name and optional list :fields.
- next/genesis/activity-types/subtype_of.sx — SubtypeOf verb; schema
  accepts an :object carrying string :child-type-cid + :parent-type-cid.

Schema bodies use nested `get` (not keyword-threading) so they are
directly evaluatable — keywords are not callable getters in the kernel.
Both registered in manifest.sx (activity-types now 7); the four bootstrap
suites' bundle counts bumped (5->7, total 36->38).

Tests: next/tests/define_type.sh (7), subtype_of.sh (6) — parse shape,
schema accept/reject, term_codec envelope round-trip.

Also load follower_graph + delivery in bootstrap_start.sh: its check-26
publish path exercises outbox:compute_delivery_set/3 (follower_graph:new
+ delivery:delivery_set), which an m2 substrate change had left unloaded
in that suite — a pre-existing red unrelated to the count bump.

Conformance 771/771; all touched next/tests green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

next/genesis/activity-types/define_type.sx

@@ -0,0 +1,34 @@
+;; next/genesis/activity-types/define_type.sx
+;;
+;; Bootstrap definition of the DefineType verb per
+;; plans/fed-sx-host-types.md (host-type federation, Phase 1).
+;; Read as data by the bundler (bootstrap.erl) — never evaluated as
+;; code. The :schema and :semantics bodies are SX source.
+;;
+;; DefineType declares a refinement type. The activity's :object is
+;; the type record:
+;;   {:name             "Post"          ;; the type's display name
+;;    :fields           (...)           ;; optional field descriptors
+;;    :refinement-schema (fn (obj) ...) ;; predicate over instances
+;;    :instance-type    "Note"}         ;; base object-type it refines
+;;
+;; The schema below validates the *activity* shape: :object present,
+;; :name a string, :fields (when present) a list. The richer
+;; per-field shape check and the registry registration land with the
+;; peer_types cache (Phase 2) — at this phase the form is pure data.
+;;
+;; Schema bodies use nested `get` rather than keyword-threading so
+;; the predicate is directly evaluatable (keywords are not callable
+;; getters in the kernel; `(-> d :k)` is not a get).
+(DefineActivity
+  :name "DefineType"
+  :doc "Declare a refinement type. :object carries :name, optional :fields, :refinement-schema, and :instance-type."
+  :schema (fn
+    (act)
+    (and
+      (not (nil? (get act :object)))
+      (string? (get (get act :object) :name))
+      (or
+        (nil? (get (get act :object) :fields))
+        (list? (get (get act :object) :fields)))))
+  :semantics (fn (state act) state))

next/genesis/activity-types/subtype_of.sx

@@ -0,0 +1,31 @@
+;; next/genesis/activity-types/subtype_of.sx
+;;
+;; Bootstrap definition of the SubtypeOf verb per
+;; plans/fed-sx-host-types.md (host-type federation, Phase 1).
+;; Read as data by the bundler (bootstrap.erl) — never evaluated as
+;; code. The :schema and :semantics bodies are SX source.
+;;
+;; SubtypeOf records a hierarchy edge between two previously-defined
+;; types. The activity's :object is the relation record:
+;;   {:child-type-cid  "bafy...child"
+;;    :parent-type-cid "bafy...parent"}
+;;
+;; The schema validates the *activity* shape: both CIDs present and
+;; string-typed. Verifying that each CID names a previously-defined
+;; type is a registry concern (it needs the type index that lands
+;; with peer_types in Phase 2), so it is deliberately out of the
+;; pure-predicate schema here — adding the edge to the hierarchy
+;; index is the :semantics' job once the registry surface exists.
+;;
+;; Schema bodies use nested `get` rather than keyword-threading so
+;; the predicate is directly evaluatable.
+(DefineActivity
+  :name "SubtypeOf"
+  :doc "Record a subtype edge. :object carries :child-type-cid and :parent-type-cid, both type CIDs."
+  :schema (fn
+    (act)
+    (and
+      (not (nil? (get act :object)))
+      (string? (get (get act :object) :child-type-cid))
+      (string? (get (get act :object) :parent-type-cid))))
+  :semantics (fn (state act) state))