Orgchain v1.1: lineage's keys, from the tree branch

Folds in the tree branch's key layer (2ea7884): lineage-keys.js and
handoff.js come over as written, with their spec vectors; the off-chain
keyring and the old UI stay behind, because v1's tree comes from the chain.

- Each holding gets its own 24-word lab root. Every node has lineage's
  keys at its place in the tree: BIP-85 org seeds, agents as accounts
  1..n of their org's seed, BIP-86 wallets and NIP-06 npubs.
- Every act is signed by whichever key holds the authorizing inscription;
  a birth hands the child its own; the lab wallet is the faucet.
- Graduation is a claim by the org's fresh root, countersigned by its
  derived key, and the derived subtree re-keys under the new root, so the
  parent's line can no longer sign for it. Adopted descendants keep theirs.
- Inspect shows each node's key path, npub, address and current holder,
  and which key signed each event; the act panel names the signing key.
- Labs saved before keys still load; their holdings sign with the lab
  wallet.
- 49 unit tests (6 new), Playwright 6/6 with key checks.

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

tests/orgchain.spec.js

@@ -99,6 +99,12 @@ test('the sample replays, any beat can be inspected, and the lab survives a relo
   await expect(page.locator('#beat-label')).toHaveText('Now · beat 7', { timeout: 15_000 });
   await page.locator('#timeline-list .ev', { hasText: 'graduate lineage from well-known' }).click();
   await expect(page.locator('#inspect-body')).toContainText('"op": "graduate"');
+  await expect(page.locator('#inspect-body')).toContainText("well-known's key");
+  await row(page, 'lineage').click();
+  await expect(page.locator('#inspect-body')).toContainText("lineage root · m/86'/1'/0'/0/0");
+  await expect(page.locator('#inspect-body')).toContainText('its own key');
+  await row(page, 'time').click();
+  await expect(page.locator('#act-key')).toHaveText("Signs as time: yolopreneur root › 1' · m/86'/1'/0'/0/0");
   expect(await page.evaluate(() => document.documentElement.scrollWidth <= innerWidth)).toBe(true);
   await page.reload();
   await expect(page.locator('#tree-rows .sel')).toHaveCount(12);