[CanReader]

What this changes

Defines DEBUG for Debug builds on MSVC with a $<CONFIG:Debug> generator expression. Visual Studio is a multi-config generator and ignores CMAKE_BUILD_TYPE, so the old check never defined it on Windows. The Linux path is unchanged.

Merge CanReader/SleakEngine#225 first. Windows Debug builds need its Vector.hpp fix to compile. CI here builds against the engine's fix/windows-debug-build branch until then.

Why

Everything behind #ifdef DEBUG was compiled out on Windows, including -world, which quietly fell back to the main menu. The engine's Logger.cpp and VulkanBuffer.cpp use it too.

How it was verified

• Builds on Windows (MSVC 2022, Debug) with the engine branch
• Loaded a world (-world HotReloadTest, DX11) and edited flat_shader.hlsl while it ran; it reloaded
• Builds on Linux. Not rebuilt there; the non-MSVC branch is the same as before.
• Placed and broke blocks
• Saved, quit, reloaded, and the world was intact

Only a build flag changed, so placing, breaking and saving weren't exercised. Tested locally on top of main plus #90, not on top of the current staging.

Checklist

• Shader changes updated all backend variants and the committed .spv (no shader changes)
• Save format changes bumped WorldMeta::CURRENT_VERSION and handle old worlds (no save changes)
• Collision changes kept the single-pass MTV resolution intact (no collision changes)
• New event handlers are unregistered on scene teardown (no new handlers)