fed-sx-types Phase 6: DefineTrigger verb + trigger_registry

The trigger declaration layer (fed-sx-triggers-loop.md Phase 1): bind an
activity-type to a durable flow so an arriving activity can fan out into
a business flow.

- next/genesis/activity-types/define_trigger.sx — the DefineTrigger verb
  (DefineActivity form, nested-get schema). :object carries
  :activity-type, :flow-name, optional :guard / :actor-scope.
- next/kernel/trigger_registry.erl — pure core + registered gen_server,
  mirroring peer_actors/peer_types. Keyed by activity-type, multiple
  specs per type fire independently. Spec = {TriggerCid, FlowName,
  Guard, ActorScope}. Hydrates on start from a fold over DefineTrigger
  activities (restart-safe, same content-addressing as define_registry).

Manifest activity-types 7->8 (total bundle 38->39); the four bootstrap
count suites + genesis_parse bumped, and bootstrap_load's internal
timeout raised (the larger bundle's double cid:to_string was truncating).

Tests: define_trigger.sh (6), trigger_registry.sh (17). lib/erlang
771/771 + next/flow 34/34 untouched.

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

next/tests/genesis_parse.sh

@@ -56,6 +56,10 @@ cat > "$TMPFILE" <<'EPOCHS'
 (eval "(first (parse (file-read \"next/genesis/activity-types/subtype_of.sx\")))")
 (epoch 204)
 (eval "(get (apply dict (rest (parse (file-read \"next/genesis/activity-types/subtype_of.sx\")))) :name)")
+(epoch 205)
+(eval "(first (parse (file-read \"next/genesis/activity-types/define_trigger.sx\")))")
+(epoch 206)
+(eval "(get (apply dict (rest (parse (file-read \"next/genesis/activity-types/define_trigger.sx\")))) :name)")
 (epoch 19)
 (eval "(len (get (apply dict (rest (parse (file-read \"next/genesis/manifest.sx\")))) :activity-types))")
 (epoch 30)
@@ -192,7 +196,9 @@ check 201 "define_type.sx head form"    "DefineActivity"
 check 202 "define_type.sx name"         "DefineType"
 check 203 "subtype_of.sx head form"     "DefineActivity"
 check 204 "subtype_of.sx name"          "SubtypeOf"
-check 19 "manifest has 7 activity-types" "7"
+check 205 "define_trigger.sx head form" "DefineActivity"
+check 206 "define_trigger.sx name"      "DefineTrigger"
+check 19 "manifest has 8 activity-types" "8"
 check 30 "sx-artifact.sx head form"     "DefineObject"
 check 31 "sx-artifact.sx name"          "SXArtifact"
 check 32 "note.sx name"                 "Note"