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>

selfhost/main.ludic

@@ -358,6 +358,8 @@ entry {
     var vkl = join_path(home, "runtime/native/vk_mac.ll")
     if g_target_win { vkl = join_path(home, "runtime/native/vk_win.ll") }
     cmd = `{cmd} {vkt} {vkl}`
+    # the CAMetalLayer a macOS window presents through, found by name in cocoa.ll
+    if not g_target_win { cmd = `{cmd} -Wl,-needed_framework,QuartzCore` }
   }
   # A shipped Windows game is a GUI-subsystem program: started from Explorer, a
   # console-subsystem one opens a console window behind the game. mainCRTStartup keeps