feat(embedding): deferred-embed markers become log records — the sidecar recovery path is deleted

The private recovery discipline, applied to its own machinery: pending-
embed markers stop being sidecar files and become first-class log records
riding the write's OWN commit fact — embed.pending lands in the same
atomic append as its after-image (a marker can never be orphaned from its
write, or vice versa; in durable-at-ack mode it shares the write's
covering fsync — zero extra syncs), and the worker's landing commit rides
embed.landed with the inline vector. Crash recovery is now a FOLD of the
log (pending without a matching landed = recovered), skipped wholesale on
brains with no v2 history; the one-time legacy bridge folds existing
sidecar files in, migrates them as one fact, and deletes them —
idempotent under a crash mid-bridge. No code path writes the sidecar
again.

Plus the ENTITY-TRUTH digest law, found by this train's own pins:
canonical vector wrappers denormalize HNSW residue (connections + the
randomly-assigned node level) that the log deliberately does not carry —
the verification oracle digested it and would have reported false
state-differs on ~any nonzero-level node (a ~15% flake in the cutover pin
was the symptom). Both sides of every oracle comparison now normalize to
entity truth (nounEntityTruth); index residue has its own rebuild path
and is not entity state.

Pins: embed-markers-in-log 5/5 (same-generation marker, landed+fold-to-
zero, crash recovery via the log with the sidecar prefix EMPTY on disk,
legacy bridge, VFS hung-embedder ack) · deferred-embedding 5/5 unchanged
(the contract outlived its mechanism) · kill-matrix 11/11 · cutover 5/5
×10 runs (flake dead) · unit 2031/2031.

tests/integration/fact-log-v2-cutover.test.ts

@@ -174,7 +174,15 @@ describe('fact log v2 cutover — live writes land in the v2 segment format', ()
       expect(op.kind).toBe('noun')
       const canonical = await internals(reopened).storage.readNounRaw(id)
       expect(op.record!.metadata).toStrictEqual(canonical.metadata)
-      expect(op.record!.vector).toStrictEqual(canonical.vector)
+      // ENTITY TRUTH comparison: canonical wrappers denormalize HNSW residue
+      // (connections + the randomly-assigned level) that the log record
+      // deliberately reconstructs empty — strip both sides (the oracle's
+      // normalizer law) so a nonzero random level can't fake a divergence.
+      const strip = (w: unknown) => {
+        const { connections: _c, level: _l, ...rest } = w as Record<string, unknown>
+        return rest
+      }
+      expect(strip(op.record!.vector)).toStrictEqual(strip(canonical.vector))
     }
   })