perf(rendering): retire production entity partition

Route production meshes and attached particles from the exact retained PView frame ranges, while keeping the former WorldEntity partition only for standalone tests and explicit diagnostic/oracle probes. Copy retained source/count facts before arena release so world diagnostics no longer require the old partition. Record the accepted G4 visual gate and open the exact G5 production matrix.

Co-authored-by: OpenAI Codex <codex@openai.com>

docs/plans/2026-05-12-milestones.md

@@ -108,11 +108,13 @@ publication, retirement, upload, warmup, or resource backlog. Capped/uncapped
 CPU p99 is 34.7%/30.4% below Slice A and maximum frame allocation is
 84.7%/82.2% lower. The user explicitly approved Slices F–L, including both
 the F/G ECS and Slice J gameplay-owner gates, on 2026-07-24. Slice F and
-G0–G4 are implemented and G4's automated gate has zero mismatches. The portal
-scheduling/private-viewport/ACE-revisit correction passed visually while the
-retained draw cutover was temporarily reverted, so `20f9fadb` reapplies the
-cutover over those fixes for the pending connected retained-path re-gate. G5
-deletion and production-only profiling remain gated on that pass. Slice H is
+G0–G4 are complete: G4's automated gate has zero mismatches and the user
+accepted the corrected retained-path portal/revisit matrix on 2026-07-25.
+G5 cleanup is active; normal production now routes meshes and attached
+particles from the retained frame product without building the old
+`InteriorEntityPartition`. Focused route tests, 3,825 App tests / 3 skips,
+and 8,334 solution tests / 5 skips pass. The exact production-only
+performance/lifecycle matrix remains before G5 closeout. Slice H is
 complete: retained UI/frame work, exact bounded light selection, and
 pooled/borrowed/direct network I/O pass 8,292 Release tests / 5 skips and the
 seven-checkpoint connected lifecycle/reconnect gate. Slice I is active under