refactor(rendering): prepare retained particle routing

Derive attached particle owners from the exact retained PView route stream with a zero-allocation warm path. Correct G4 gate provenance, record the current production-only RDP sample, and keep G5 old-route deletion explicitly blocked until the reapplied retained cutover passes its connected visual gate.

docs/research/2026-07-25-portal-regression-closeout.md

@@ -10,9 +10,10 @@ The first connected retained-scene visual pass reported:
 4. doors, signs, portals, NPCs, and other server-spawned objects disappeared
    after repeated portal travel.
 
-This note records the root causes and the accepted correction. It does not
-reduce world radius, texture quality, particles, readiness, or retail
-presentation.
+This note records the root causes and the correction. It does not reduce world
+radius, texture quality, particles, readiness, or retail presentation. The
+correction's visual pass occurred on the temporary old-draw rollback; the
+retained-source re-gate is tracked separately below.
 
 ## Retail and protocol anchors
 
@@ -99,7 +100,11 @@ This ACE adaptation remains explicit in divergence AP-69.
 - Complete App Release suite: 3,813 passed / 3 skipped.
 - Release solution build: green with zero warnings.
 - Complete Release solution suite: 8,322 passed / 5 skipped.
-- User connected visual gate:
+- User connected correction gate on rollback route (`2c848d41`):
   - paperdoll remains visible;
   - portal transit is materially faster;
   - server-spawned objects remain after repeated travel.
+- Retained production source:
+  - `20f9fadb` reapplies exact cutover `ef1d2633` over the correction;
+  - complete Release suite: 8,326 passed / 5 skipped;
+  - connected portal/revisit visual re-gate pending before G4 acceptance.