Initial public release: OVRPlugin→OpenXR interoperability shim

An independent reimplementation of Meta's libOVRPlugin ABI on top of OpenXR, so
VrApi-era Meta Quest VR titles can run on non-Meta OpenXR runtimes (Monado,
Steam Frame) instead of being locked to Meta hardware. Original code only — no
Meta/Epic/Capcom binaries, headers, or assets. Includes a desktop harness that
drives the shim against Monado headless.

Scope/legal: interoperability; entitlement handling is out of scope. See README
for the legal/scope section and docs/ for the research trail and design notes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D6sFYGXZPsq3v7xtcDES6g

shim/README.md

@@ -0,0 +1,54 @@
+# libOVRPlugin.so shim (OVRPlugin v1.51 -> OpenXR)
+
+Drop-in replacement for RE4 VR's libOVRPlugin.so that re-exports the ovrp_* symbols
+backed by OpenXR (Monado) instead of Meta's libvrapi.so. See ../HOST.md, ../SHIM-SCOPE.md.
+
+## Layout
+- include/ovrplugin_shim.h  — OVRPlugin v1.51 C ABI (types + core protos; self-checking
+  _Static_asserts on binary-verified struct sizes).
+- gen_stubs.sh              — generates src/stubs.c from ../analysis/shim_surface.txt.
+- src/stubs.c  (generated)  — 224 stubs: 101 Unsupported(-1004), 32 no-op Success(0),
+  91 NotYetImplemented(-1005).
+- src/core.c               — the 15 header-prototyped core fns (frame loop/init/poses/
+  controller/system), currently TODO stubs returning -1005 with outputs zeroed.
+
+## Build (host, for validation)
+```
+cc -std=c11 -Wall -shared -fPIC -fvisibility=hidden -Iinclude src/stubs.c src/core.c \
+   -o build/libOVRPlugin.so
+```
+Status: builds; exports exactly 239 ovrp_ symbols (1:1 with shim_surface.txt, 0
+missing/extra); dlopen+dlsym verified. This is the SKELETON — it loads and resolves,
+it does not yet drive VR (core fns are TODO).
+
+## Real target build (deployable) — TODO
+Must be aarch64 / Android (bionic) since it runs inside Lepton. Use the Android NDK:
+```
+$NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang \
+   -std=c11 -shared -fPIC -fvisibility=hidden -Iinclude src/stubs.c src/core.c \
+   -o build/arm64/libOVRPlugin.so
+```
+(host build only proves the C + symbol coverage; NDK build is the artifact that
+replaces the real lib in the APK.)
+
+## Modules (current)
+- include/ovrplugin_shim.h  — OVRPlugin v1.51 ABI (types, structs, core protos).
+- src/stubs.c (generated)   — 221 stubs (unsupported/no-op/TODO).
+- src/core.c                — lifecycle + frame loop + poses (-> xr_runtime).
+- src/xr_runtime.{h,c}      — OpenXR engine: session, frame loop, swapchains.
+- src/vk_session.c          — Vulkan-typed: xrCreateSession binding + image enum.
+- src/layers.c              — ovrp_SetupLayer / GetLayerTexture2 / StageCount.
+- tests/harness.c           — Path B smoke test (see ../TESTING.md).
+Build adds: -Ithird_party/openxr -Ithird_party/vulkan, and src/{core,xr_runtime,
+vk_session,layers,stubs}.c. 20 OpenXR fns used; 239/239 ovrp_ exported.
+
+## Done so far
+Session lifecycle, frame loop (xrWaitFrame/Begin/EndFrame), poses (xrLocateViews/
+Space), swapchains (xrCreateSwapchain from ovrpLayerDesc, acquire/wait/release,
+XrCompositionLayerProjection submit). Vulkan binding from Initialize5 args [VERIFIED].
+
+## Next (see ../TESTING.md for the test plan)
+1. NDK arm64 build (host build is validation only).
+2. [ANDROID-TODO] JavaVM/activity -> XrInstanceCreateInfoAndroidKHR + xrInitializeLoaderKHR.
+3. Input action sets (controllers/hands); depth layer; GetVulkan*ExtensionsKHR mapping.
+4. Repack APK (real entitlement — you own it); test on Quest 2.