docs(spec): the field ledger's notes and the liveness README cite a commit, or say what the number stood for, in place of dead tracker numbers (#20891)

Part of #20234

Clause-②: no

Liveness slice 4b (claim `5913437610`), the last slice of the liveness
stage. In `field.json` (11 sites) and `liveness/README.md` (29), each
citation of a tracker number answering 404 now names a commit in this
repository or, where the number alone carried the meaning, says that
meaning in words. 8 `note` / `_note` leaves in `field.json` and 14
README lines change, and nothing else does; no number is added, and no
README table row, heading or date moves. The 16 dead numbers now occur 0
times across every ledger and the README. One `@objectstack/spec` patch
changeset. This says `Part of`: the card's stage 11 (the hand-written
parts of `migrations/registry.ts`) is still open.

Local runs at `e74311d471`: build 71/71; spec `local` 580 files pass;
spec `repo` 42 of 46 pass; spec `typecheck` and the lint package's
liveness test pass; 58 derived gates, 57 exit 0
(`check:platform-checklist`: the pre-existing `auth-plugin.ts#twoFactor`
anchor and the `picklist` capability the checklist does not classify
yet; neither is touched here, and the gate is not per-PR CI). Lint:
ESLint's config matches none of the 3 changed files (3 "no matching
configuration" results, 0 errors); type-aware linting is never enabled.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01Sfe5YjBLwB9J3y8fvm2xq1)_

Co-authored-by: Claude <noreply@anthropic.com>

Author: objectstack-fleet[bot]

.changeset/20234-liveness-ledger-provenance-anchors-4b.md

@@ -0,0 +1,15 @@
+---
+'@objectstack/spec': patch
+---
+
+Notes in the `field` liveness ledger and sentences in the ledger README that cited a tracker number which no longer resolves now either cite a commit in this repository or say in words what the number stood for
+
+Clause-②: no
+
+Eleven citations in the `field` ledger's notes and twenty-nine in `liveness/README.md` pointed at
+a GitHub issue or pull request that no longer exists, so they led nowhere. Each one now either
+names the commit that did or recorded what the number pointed at or, where the number alone
+carried the meaning, says that meaning in words. The `liveness/` ledgers and their README ship in
+this package's tarball, which is why this is a release note at all. Prose only: no row's status,
+evidence, proof, producer or date changes, no README table row or heading is added, removed or
+renamed, and no schema, export or runtime behaviour changes.