Added foveated rendering for the Quest

- Eyes render under a VK_EXT_fragment_density_map: full rate around each eye's forward direction,
  2x2 then 4x4 pixel blocks towards the edges ([vr] foveation = off|low|medium|high, default off).
  XR_FB_foveation cannot help here: the runtime's maps only shape passes drawing into its
  swapchain, and the eyes reach it through a copy.
- aurora-main/patches/dawn/aurora_fdm.inc: Dawn enables the extension only on request and for
  dynamic rendering, flags every render pipeline, and chains an immutable RG8 map into any pass
  whose first color attachment is a view bound to one (ABI: include/aurora/dawn_fdm_abi.h).
- android/Build-QuestDawn.ps1 builds the pinned Dawn revision with those patches for arm64
  (dawn-build CI flags, protobuf off) into a cached package; Build-Quest.ps1 links it
  (-StockDawn opts out) and AuroraDawnProvider.cmake enables the ABI from its manifest.
- lib/gfx/foveation.hpp generates the maps (32 px per texel, densities 255/127/63); an eye is
  foveated only when single_pass_eyes draws it in one render pass. Menus never are.
- Live level from the headset panel's VR tab and the launcher; the launch decides whether the
  device has maps. debug.wiicompiled.foveation and debug.wiicompiled.fdm for A/B.
- Tests: Foveation cases in gx_fifo_tests, mkw_vr_config_tests. Docs: OPENXR.md, quest-port.md.

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

runtime/CMakeLists.txt

@@ -395,6 +395,12 @@ target_include_directories(mkw_frame_interpolation_pacing_tests PRIVATE "${CMAKE
 target_link_libraries(mkw_frame_interpolation_pacing_tests PRIVATE mkw::toml11)
 target_compile_features(mkw_frame_interpolation_pacing_tests PRIVATE cxx_std_20)
 add_test(NAME mkw_frame_interpolation_pacing_tests COMMAND mkw_frame_interpolation_pacing_tests)
+# [vr] settings the headset renderer reads: single_pass_eyes and the Quest's foveation.
+add_executable(mkw_vr_config_tests tests/vr_config_tests.cpp)
+target_include_directories(mkw_vr_config_tests PRIVATE "${CMAKE_CURRENT_LIST_DIR}/include")
+target_link_libraries(mkw_vr_config_tests PRIVATE mkw::toml11)
+target_compile_features(mkw_vr_config_tests PRIVATE cxx_std_20)
+add_test(NAME mkw_vr_config_tests COMMAND mkw_vr_config_tests)
 add_executable(mkw_platform_paths_tests "${CMAKE_CURRENT_LIST_DIR}/tests/platform_paths_tests.cpp")
 target_link_libraries(mkw_platform_paths_tests PRIVATE mkw_platform)
 target_compile_features(mkw_platform_paths_tests PRIVATE cxx_std_17)