fix(vulkan): MSAA crash on AMD RADV due to vkCreateRenderPass2 null dispatch

Instance was created with Vulkan 1.1 but depthResolveSupported_ was gated
on the physical device's API version (1.2+ on RADV). This caused
vkCreateRenderPass2 (core 1.2) to dispatch through a null function pointer
when MSAA was enabled. Now requests 1.2 instance with 1.1 minimum fallback
and gates depth resolve on the actual instance API version. Also removes
all diagnostic crash-phase instrumentation from the previous investigation.

include/rendering/vk_context.hpp

@@ -246,6 +246,9 @@ private:
     bool createDepthResolveImage();
     void destroyDepthResolveImage();
 
+    // Actual Vulkan API version the instance was created with (gates core 1.2 calls)
+    uint32_t instanceApiVersion_ = VK_API_VERSION_1_1;
+
     // MSAA depth resolve support (for sampling/copying resolved depth)
     bool depthResolveSupported_ = false;
     VkResolveModeFlagBits depthResolveMode_ = VK_RESOLVE_MODE_NONE;