Port of the Dear ImGui Vulkan renderer (imgui_impl_vulkan) into the
imgui-lwjgl3 module:
- ImGuiImplVulkan renderer with descriptor sets, pipeline creation and
  font atlas upload; shader SPIR-V shipped as classpath resources
- ImGuiImplVulkanH helper structures
- createVulkanSurface() helpers for the GLFW and SDL3 backends
- imgui-app: VULKAN backend with WindowVulkan (swapchain, render pass,
  per-frame sync objects and resize handling)
- example: ExampleVulkan smoke test

Co-authored-by: DeepSeek <[email protected]>

Match the pinned Dear ImGui 1.92.7 backend: single descriptor set with
COMBINED_IMAGE_SAMPLER at set 0, one pool size, one bind per draw, and
the upstream shader bytecode shipped as resources. Drops the separate
sampler descriptor set, the deprecated addTexture overload and the
second pool-size constant.

Co-authored-by: DeepSeek <[email protected]>

createFontsTexture() declared locals shadowing the fontImage/fontMemory/
fontImageView/fontDescriptorSet fields, so destroyFontsTexture() never
released the atlas resources. Also expand the wildcard Vulkan imports in
WindowVulkan to satisfy AvoidStarImport.

Co-authored-by: DeepSeek <[email protected]>