feat(render3d): Vulkan in a macOS window through MoltenVK; window built-ins take a slice's elements; the NEAR_FADE SPIR-V

- a CAMetalLayer on the view (cocoa.ll win_metal_layer), VK_EXT_metal_surface, QuartzCore linked
  with Vk.*; the drawable measured after the layer sets the backing scale
- vk_mac.ll opens MoltenVK directly after any loader: a bundle ships only libMoltenVK.dylib
- a covered window is not presented to (win_visible); one frame in flight on macOS
  (R3D_VK_INFLIGHT), with images, buffers and descriptor pools held until it is done
- win_held / win_mouse / win_pad / win_touch / win_text / win_present pass slice elements (arg_buf):
  every windowed program died on its first input poll
- variants.list and SPIR-V for the three NEAR_FADE foliage programs

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/ludic-cli/build.ludic

@@ -102,7 +102,8 @@ function gl_link_flags(ll: pointer) -> pointer {
 function vk_link_flags(ll: pointer) -> pointer {
   if not shq(`grep -q "@lvk_" {ll}`) { return "" }
   let home = ludic_home()
-  return ` {home}runtime/native/vk_thunks.ll {home}runtime/native/vk_mac.ll`
+  # QuartzCore: the CAMetalLayer a window presents through (cocoa.ll finds the class by name)
+  return ` {home}runtime/native/vk_thunks.ll {home}runtime/native/vk_mac.ll -Wl,-needed_framework,QuartzCore`
 }
 
 # A program that uses Http.* calls the @hs_* transport; link http.ll and Foundation only