Vulkan: extract cubemap IBL prefilter to vk_cubemap_prefilter.c

Move filterDef helpers, prefilter renderpass/FB/pipeline, create/destroy,
vk_clear_cube_color, readback/SH extraction, and vk_generate_cubemaps out of
vk.c. Wrap translation unit in VK_CUBEMAP. Update MSVC and ARCHITECTURE.md.

Co-authored-by: Tim Fox <timfox@outlook.com>

Author: cursoragent

docs/ARCHITECTURE.md

@@ -59,6 +59,7 @@ src/
 │   │   ├── vk_shutdown.c          vk_shutdown, wait-idle, release_resources (split from vk.c)
 │   │   ├── vk_postfx_passes.c     Bloom, SSAO/HBAO, OIT, SSR passes (split from vk.c)
 │   │   ├── vk_clear_attachments.c In-pass color/depth clear + dynamic color write mask (split from vk.c)
+│   │   ├── vk_cubemap_prefilter.c IBL cubemap prefilter, SH extraction, vk_generate_cubemaps (split from vk.c)
 │   │   ├── vk_fluidsim.c/h       Fluid simulation module
 │   │   ├── vk_postfx.c/h         PostFX (SSR, atmosphere, wind)
 │   │   ├── vk_flashlight.c/h     Projected texture system

src/platform/win32/msvc2017/vulkan.vcxproj

@@ -277,6 +277,7 @@
     <ClCompile Include="..\..\..\renderers\vulkan\vk_shutdown.c" />
     <ClCompile Include="..\..\..\renderers\vulkan\vk_postfx_passes.c" />
     <ClCompile Include="..\..\..\renderers\vulkan\vk_clear_attachments.c" />
+    <ClCompile Include="..\..\..\renderers\vulkan\vk_cubemap_prefilter.c" />
     <ClCompile Include="..\..\..\renderers\vulkan\vk_device.c" />
     <ClCompile Include="..\..\..\renderers\vulkan\vk_flashlight.c" />
     <ClCompile Include="..\..\..\renderers\vulkan\vk_flares.c" />

src/platform/win32/msvc2017/vulkan.vcxproj.filters

@@ -154,6 +154,9 @@
     <ClCompile Include="..\..\renderers\vulkan\vk_clear_attachments.c">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\renderers\vulkan\vk_cubemap_prefilter.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\renderers\vulkan\vk_attachments.c">
       <Filter>Source Files</Filter>
     </ClCompile>