fix: restore WMO wall collision threshold to cos(50°) ≈ 0.65

The wall/floor classification threshold was lowered from 0.65 to 0.35
in a prior optimization commit, causing surfaces at 35-65° from
horizontal (steep walls, angled building geometry) to be classified as
floors and skipped during wall collision. This allowed the player to
clip through angled WMO walls.

Restore the threshold to 0.65 (cos 50°) in both the collision grid
builder and the runtime checkWallCollision skip, matching the
MAX_WALK_SLOPE limit used for slope-slide physics.

src/rendering/wmo_renderer.cpp

@@ -2677,10 +2677,11 @@ void WMORenderer::GroupResources::buildCollisionGrid() {
         triNormals[i / 3] = normal;
 
         // Classify floor vs wall by normal.
-        // Wall threshold matches the runtime skip in checkWallCollision (absNz >= 0.35).
+        // Wall threshold matches MAX_WALK_SLOPE (cos 50° ≈ 0.6428): surfaces steeper
+        // than 50° from horizontal are walls. Must match checkWallCollision runtime skip.
         float absNz = std::abs(normal.z);
-        bool isFloor = (absNz >= 0.35f);  // ~70° max slope (relaxed for steep stairs)
-        bool isWall = (absNz < 0.35f);    // Matches checkWallCollision skip threshold
+        bool isFloor = (absNz >= 0.65f);
+        bool isWall = (absNz < 0.65f);
 
         int cellMinX = std::max(0, static_cast<int>((triMinX - gridOrigin.x) * invCellW));
         int cellMinY = std::max(0, static_cast<int>((triMinY - gridOrigin.y) * invCellH));
@@ -3273,9 +3274,11 @@ bool WMORenderer::checkWallCollision(const glm::vec3& from, const glm::vec3& to,
                 float horizDist = glm::length(glm::vec2(delta.x, delta.y));
 
                 if (horizDist <= PLAYER_RADIUS) {
-                    // Skip floor-like surfaces — grounding handles them, not wall collision
+                    // Skip floor-like surfaces — grounding handles them, not wall collision.
+                    // Threshold matches MAX_WALK_SLOPE (cos 50° ≈ 0.6428): surfaces steeper
+                    // than 50° from horizontal must be tested as walls to prevent clip-through.
                     float absNz = std::abs(normal.z);
-                    if (absNz >= 0.35f) continue;
+                    if (absNz >= 0.65f) continue;
 
                     const float SKIN = 0.005f;        // small separation so we don't re-collide immediately
                     // Push must cover full penetration to prevent gradual clip-through
@@ -3578,7 +3581,7 @@ float WMORenderer::raycastBoundingBoxes(const glm::vec3& origin, const glm::vec3
                 const glm::vec3& v2 = verts[indices[triStart + 2]];
                 glm::vec3 triNormal = group.triNormals[triStart / 3];
                 if (glm::dot(triNormal, triNormal) < 0.5f) continue;  // degenerate
-                // Wall list pre-filters at 0.35; apply stricter camera threshold
+                // Wall list pre-filters at 0.65; apply stricter camera threshold
                 if (std::abs(triNormal.z) > MAX_WALKABLE_ABS_NORMAL_Z) {
                     continue;
                 }