Hide Navara infrastructure stems and data pack meshes behind walls, terrain and the Earth

Navara draws its transparent scene after the post effects into a target without the scene depth, so stems and pack polygons and images painted through 3D tiles. A scene-depth test now drops each of their fragments behind the depth Navara packs after its opaque pass; they stay in the transparent pass, so their look in the open is unchanged (scripts/qa-edge-occlusion.mjs compares it with the previous build). Wind flow was already hidden and is kept as a guard in the same scenario.

scripts/package-boundaries.json

@@ -3706,6 +3706,7 @@
       "src/layers/awareness/render/navara.js",
       "src/layers/infrastructure/render/navara.js",
       "src/layers/shared/render/navaraStems.js",
+      "src/layers/shared/render/navaraSceneDepth.js",
       "src/layers/submarineCables/render/navara.js",
       "src/layers/directions/render/navara.js",
       "src/layers/traffic/render/navara.js",