docs: provenance caveat on the §8 fourth mode — bgz-tensor predates turbovec/PolarQuant/helix

Mirrors lance-graph 88dcf6b: the fourth-mode paragraph now notes the
adaptive codec was engineered before today's lane inventory existed and
points at the queued engineering follow-up review
(TD-BGZ-TENSOR-PRE-LANE-REVIEW: i4+i2 cascade vs turbovec
Lloyd-Max/NativeLut, Hadamard vs PolarQuant rotation findings, residual
coding vs helix — consume-the-lane / demarcate / retire).

Knowledge-doc suite green (117/117).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K3RyLEbuNSHxxB3NTTrGki

Author: claude

.claude/knowledge/pr-x12-h268-morton-wgpu-synergies.md

@@ -249,7 +249,12 @@ Hadamard-rotated residual in a three-tier LFD split
 `Passthrough` (exact original stored — no index+residual at all), the
 next ~20% get an i8 residual, the bottom ~70% the i4+i2 cascade — index
 PLACES, residual CORRECTS, and the mold is never forced on rows it
-doesn't fit. It is the continuous-field exit
+doesn't fit. Provenance caveat: bgz-tensor predates turbovec/PolarQuant
+and helix — this records what ships, not current best practice; an
+engineering follow-up review is queued (lance-graph
+`TD-BGZ-TENSOR-PRE-LANE-REVIEW`: reconcile the i4+i2 cascade vs turbovec
+Lloyd-Max/NativeLut, Hadamard vs the PolarQuant rotation findings,
+residual coding vs helix — consume-the-lane / demarcate / retire). It is the continuous-field exit
 where a bare 256-level index terraces (e.g. elevation); categorical
 surfaces (`Signed360` normals, narrow colour) stay flat. Out-of-row like
 `Signed360`; the in-row refinement budget remains the turbovec nibble