fix(world): throttle shadows and tune high preset

docs/technical/map-lod.md

@@ -25,7 +25,7 @@ Current behavior:
 | -------- | ------------------: | --- | ------------------------------------- |
 | `low`    |                 10m | On  | Always use `*-LOD` models             |
 | `medium` |                 20m | On  | Always use `*-LOD` models             |
-| `high`   | Current default 50m | Off | Regular model up to 10m, then `*-LOD` |
+| `high`   |                 35m | Off | Regular model up to 10m, then `*-LOD` |
 | `ultra`  |                 50m | Off | Regular model up to 20m, then `*-LOD` |
 
 The unload distance stays slightly larger than the load distance to avoid rapid mount/unmount flickering when the player stands near a boundary.

docs/technical/map-performance.md

@@ -158,9 +158,11 @@ Current runtime values:
 
 ```txt
 chunkSize: 35
-loadRadius: 45
-unloadRadius: 45
-updateInterval: 350ms
+low load/unload radius: 10m / 18m
+medium load/unload radius: 20m / 30m
+high load/unload radius: 35m / 45m
+ultra load/unload radius: 50m / 65m
+updateInterval: 250ms
 fog near: 30
 fog far: 45
 ```

docs/technical/scene-runtime.md

@@ -91,6 +91,12 @@ Activation des ombres -> Ombres prêtes -> Gameplay prêt
 
 This keeps the loading overlay visible until the renderer shadow map, shadow-casting light, and mounted scene graph have all been explicitly refreshed.
 
+After the warmup, shadow maps switch back to manual refreshes driven by `Lighting`.
+The sun still follows the player camera, but the shadow map is only marked dirty
+when the camera has moved enough and a short refresh interval has elapsed. This
+keeps shadows present after loading without paying for a full shadow render every
+frame across the dense vegetation chunks.
+
 The debug physics scene is ready when:
 
 ```ts