Orgchain v1.8: belts cross holdings, and a graduate becomes its own holding

From the operator's notes on trying v1.6.1. An award's recipient may sit in
any holding, so a registry like well-known can certify an agent it doesn't
hold (say, after the agent pays it). A graduated org already held its own
root; now it is a holding of its own too: it and its subtree re-root under
it, it joins the Holdings list with its own tree and timeline, mines its
share and can be funded, and its parent's tree keeps a row for it that opens
it. Events that touch two holdings (a belt across them, a graduation) show in
both timelines, and the holding that acted gets the last-act credit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H4upF5LVwmPDDqrhdUfnXh

tests/lab.test.js

@@ -85,8 +85,9 @@ test('the yolopreneur sample is six beats of the drawing in docs/lineage.md', ()
   const s = state(lab, {}), named = name => [...s.nodes.values()].find(x => x.name === name);
   assert.ok(s.log.every(e => e.ok));
   assert.equal(s.nodes.get(root).name, SAMPLE);
-  assert.deepEqual([...s.nodes.values()].filter(x => x.root === root).length, 12);
+  assert.deepEqual([...s.nodes.values()].filter(x => x.root === root).length, 11);
   assert.equal(named('lineage').edge, 'adopted');
+  assert.deepEqual(s.roots.map(r => r.name), ['yolopreneur', 'lineage']); // graduated: a holding of its own
   assert.deepEqual(named('sol').badges.map(b => `${b.skill}:${b.belt}`), ['launch:green']);
   assert.deepEqual(named('time').children.map(id => s.nodes.get(id).name), ['luna', 'sol', 'astra', 'docscope', 'dollhouse', 'doodleloop', 'hearthframe']);
   assert.deepEqual([2, 3, 4, 5].map(upTo => state(lab, { upTo }).nodes.size), [1, 3, 8, 12]);