Merge campaign-cc6a: CC6a preview foundation + CC6b-PRE animation half, review-closed

CC6a (index->ObjDesc factory + static-pose offscreen renderer) and
CC6b-PRE (idle loop, rotation, zoom, alternate-setup plumbing) both
closed through dual-lens review -> fix round -> narrow re-review. The
branch carries its own cross-branch renumbering (TS-84, ISSUES #403) so
this merge is number-clean against the CC4 rows.

Notable review outcomes carried in: the barber refutation (chargen has
NO alternate-setup checkbox — all five write sites are gmBarberUI), the
idle-by-default finding with its corrected InitializePage evidence, and
the 180-degree initial heading owed to the mount half.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

# Conflicts:
#	docs/ISSUES.md
#	docs/architecture/retail-divergence-register.md

docs/ISSUES.md

@@ -24,6 +24,39 @@ What does NOT go here:
 - Every session: scan OPEN issues at start; promote/close anything we touched during the session before ending.
 - Promoting to a Phase: mark as `DONE (promoted to Phase X)` + commit SHA where the Phase entry landed.
 
+## #403 — Consolidate RetailAnimationCyclePlayback into LiveEntityAnimationPresenter's legacy branch
+
+**Status:** OPEN (post-CC consolidation follow-up)
+**Severity:** LOW
+**Filed:** 2026-08-15 (Campaign CC slice CC6b-PRE review fix round, F5)
+**Component:** `src/AcDream.Core/Physics/RetailAnimationCyclePlayback.cs`,
+`src/AcDream.App/Rendering/LiveEntityAnimationPresenter.cs`
+
+`RetailAnimationCyclePlayback` (advance-with-wrap + lerp/slerp) is a Core,
+pure, unit-tested extraction of the SAME algorithm
+`LiveEntityAnimationPresenter.Present`'s legacy (no-`AnimationSequencer`)
+branch already carries inline for NPC idle cycles
+(`CurrFrame += legacyAdvanceSeconds * Framerate` with the same modulo wrap,
+plus its own private `TryResolvePartFrame` doing the same frame-bracket
+lerp/slerp). The chargen preview (`ChargenPreviewAnimator`) consumes the
+new shared type; the two implementations were deliberately left
+un-consolidated at CC6b-PRE — `LiveEntityAnimationPresenter` is live,
+heavily-tested, in-flight production entity-rendering code with zero
+relation to the preview-only feature that motivated the extraction, so
+touching it was judged out of that slice's blast radius.
+
+That decision has no tracked owner. Someone should, in a dedicated pass
+after Campaign CC closes: redirect `LiveEntityAnimationPresenter`'s inline
+copy through `RetailAnimationCyclePlayback` (a behavior-preserving
+mechanical swap — same formulas, same order of operations) and delete the
+duplicate. Verify byte-identical output first (a differential test against
+the pre-change behavior over a representative NPC idle set) before landing.
+
+**Acceptance:** one call site for the advance-with-wrap + lerp/slerp
+algorithm; `LiveEntityAnimationPresenter`'s legacy branch calls
+`RetailAnimationCyclePlayback` instead of reimplementing it; no behavior
+change to any currently-animated NPC.
+
 ## #402 — Flaky test: Streaming.LandblockBuildFactoryTests.Build_UsesTheSuppliedSharedReaderGate
 
 **Status:** OPEN (flake, not a regression)