Make InvisibleTrap objects invisible and non-collidable

Event objects like Fire Festival Fury Trap and Mercutio Post use
SpellObject_InvisibleTrap.m2 models which were rendering as white
tiles using WHITE1.BLP texture. These are meant to be invisible
spell trigger objects that should not obstruct player movement.

Changes:
- Added isInvisibleTrap flag to M2ModelGPU struct
- Detect models with "invisibletrap" in name during loading
- Skip rendering invisible trap instances in render loop
- Disable all collision checks (floor/wall/occlusion) for invisible traps
- Objects remain functional for spell casting but are now invisible

test_gameobject_display.cpp

@@ -0,0 +1,36 @@
+#include <iostream>
+#include "pipeline/dbc.hpp"
+#include "pipeline/asset_manager.hpp"
+
+int main() {
+    wowee::pipeline::AssetManager assetManager;
+    assetManager.initialize("Data");
+
+    auto godi = assetManager.loadDBC("GameObjectDisplayInfo.dbc");
+    if (!godi || !godi->isLoaded()) {
+        std::cerr << "Failed to load GameObjectDisplayInfo.dbc\n";
+        return 1;
+    }
+
+    std::cout << "GameObjectDisplayInfo.dbc loaded with " << godi->getRecordCount() << " records\n\n";
+
+    // Check displayIds 35 and 1287
+    uint32_t targetIds[] = {35, 1287};
+    for (uint32_t targetId : targetIds) {
+        bool found = false;
+        for (uint32_t i = 0; i < godi->getRecordCount(); i++) {
+            uint32_t displayId = godi->getUInt32(i, 0);
+            if (displayId == targetId) {
+                std::string modelName = godi->getString(i, 1);
+                std::cout << "DisplayId " << displayId << ": " << modelName << "\n";
+                found = true;
+                break;
+            }
+        }
+        if (!found) {
+            std::cout << "DisplayId " << targetId << ": NOT FOUND\n";
+        }
+    }
+
+    return 0;
+}