fix(rendering): defer descriptor set destruction during streaming unload

M2 destroyInstanceBones and WMO destroyGroupGPU freed descriptor sets
and buffers immediately during tile streaming, while in-flight command
buffers still referenced them — causing DEVICE_LOST on AMD RADV.

Now defers GPU resource destruction via deferAfterFrameFence in streaming
paths (removeInstance, removeInstances, unloadModel). Immediate
destruction preserved for shutdown/clear paths that vkDeviceWaitIdle
first.

Also: vkDeviceWaitIdle before WMO backfillNormalMaps descriptor rebinds,
and fillModeNonSolid added to required device features for wireframe
pipelines on AMD.

src/rendering/vk_context.cpp

@@ -290,6 +290,7 @@ bool VkContext::selectPhysicalDevice() {
     vkb::PhysicalDeviceSelector selector{vkbInstance_};
     VkPhysicalDeviceFeatures requiredFeatures{};
     requiredFeatures.samplerAnisotropy = VK_TRUE;
+    requiredFeatures.fillModeNonSolid = VK_TRUE;  // wireframe debug pipelines
     selector.set_surface(surface)
             .set_minimum_version(1, 1)
             .set_required_features(requiredFeatures)