Add 'static-simple' collider mode documentation and updates

AGENTS.md

@@ -94,6 +94,7 @@ This is not:
   - `none` = no collider
   - `terrain` = heightfield collider, static only
   - `static` = triangle mesh collider, fixed only
+  - `static-simple` = voxel-boxified fixed compound collider for static environment use
   - `dynamic` = convex decomposition into compound collider, dynamic/kinematic capable
   - `simple` = one cheap primitive or one convex hull
 

architecture.md

@@ -771,6 +771,7 @@ type ModelInstanceCollisionMode =
   | "none"
   | "terrain"
   | "static"
+  | "static-simple"
   | "dynamic"
   | "simple";
 
@@ -799,6 +800,7 @@ Rules:
   - `none` = no collider
   - `terrain` = heightfield collider, static only
   - `static` = triangle mesh collider, fixed only
+  - `static-simple` = voxel-boxified fixed compound collider for static environment use
   - `dynamic` = convex decomposition into compound collider, dynamic/kinematic capable
   - `simple` = one cheap primitive or one convex hull
 - initial support may be staged, but unsupported modes must fail clearly instead of silently degrading to random approximations

roadmap.md

@@ -374,6 +374,7 @@ The tool becomes more than brush-only by supporting imported assets, authored li
   - none = no collider
   - terrain = heightfield collider, static only
   - static = triangle mesh collider, fixed only
+  - static-simple = voxel-boxified fixed compound collider for static environment use
   - dynamic = convex decomposition into compound collider, dynamic/kinematic capable
   - simple = one cheap primitive or one convex hull
 - generated collision survives save/load through canonical settings and deterministic rebuild behavior

testing.md

@@ -186,6 +186,7 @@ Examples:
 - imported-model collider generation honors the authored mode semantics:
   - terrain -> heightfield
   - static -> triangle mesh
+  - static-simple -> compound box pieces
   - dynamic -> compound convex pieces
   - simple -> primitive or convex hull
 - unsupported imported-model collision modes fail clearly instead of producing silent garbage