refactor(M03): extract terrain chunk queue planner

RENDER.md

@@ -964,6 +964,19 @@ $exe = Join-Path $env:TEMP 'godot-4.6.1-openwc\Godot_v4.6.1-stable_win64.exe'
   scene-free contract is formula evidence only; asset-backed p95/p99 and visual
   acceptance remain required.
 
+## 2026-07-16 Terrain Chunk Geometry Queue Planner Extraction
+
+- `TerrainChunkGeometryQueuePlanner` now compares current and desired chunk state
+  and returns fresh chunk create/remove request arrays.
+- LOD mismatches and absent chunks retain the existing request shape; creates
+  remain sorted by horizontal distance from chunk origin to streaming focus.
+- Desired tile LOD still removes every current chunk, while sparse parsed chunk
+  records retain the existing tile-origin distance fallback.
+- `StreamingWorldLoader` still owns queue storage/drains, removal-first execution,
+  the shared `chunk_geometry` budget lane and every Mesh/Node/RID side effect.
+- Cache formats, quality profiles and visual rules are unchanged. Asset-backed
+  p95/p99 and visual acceptance remain required.
+
 ## 2026-07-16 World Environment Snapshot Facade
 
 - `WorldEnvironmentSnapshot` carries one immutable finite time-of-day value,