fed-sx-m2: Step 2a — Person/Service/Group genesis object-types

Three new DefineObject artefacts in next/genesis/object-types/ for
the canonical actor object-types per design §9.1:

- Person: human-controlled identity (display name + handle + bio)
- Service: automated / programmatic actor (bot, feed, organisation)
- Group: multi-controller actor (member-set managed via Add/Remove)

Each is a small SX form with :name / :doc / :schema, identical
shape to existing object-types (note.sx, sx-artifact.sx etc) so the
existing bootstrap:populate_registry walk picks them up without
code changes. Manifest extended (object-types: 10 -> 13, total
entries: 31 -> 34).

Tests:
- genesis_parse.sh +7 cases (head form, :name, manifest membership);
  57/57.
- Hardcoded counts bumped in bootstrap_read.sh, bootstrap_load.sh,
  bootstrap_populate.sh, bootstrap_start.sh.
- bootstrap_build.sh 12/12 (bundle CID computed dynamically).

Conformance 761/761 preserved. 211/211 across 12 Step-2-adjacent
suites.

next/tests/bootstrap_start.sh

@@ -116,9 +116,9 @@ check() {
 check 10  "bootstrap module loaded"           "bootstrap"
 check 20  "whereis(nx_kernel) is Pid"         "true"
 check 21  "activity_types count = 3"          "3"
-check 22  "object_types count = 10"           "10"
+check 22  "object_types count = 13"           "13"
 check 23  "projections count = 7"             "7"
-check 24  "total entries = 31"                "31"
+check 24  "total entries = 34"                "34"
 check 25  "fresh log_tip = 0"                 "0"
 check 26  "publish advances tip to 1"         "1"
 check 27  "actor_id = alice"                  "true"