Add controller input and a laser-pointer-driven menu quad

- xr_input.c/h: an OpenXR action set (aim pose, trigger/select click, a
  menu-toggle button) plus ray/quad hit-testing, and a visible
  laser-pointer line drawn from the controller toward the hit point.
- xr_menu.c/h + MenuOverlay.java: a second composition-layer quad,
  toggled by a controller button, showing an off-screen, never-attached
  Android View tree (one "Keyboard" button so far) driven by synthetic
  touch events computed from the laser ray's hit UV.
- Migrate gl4es from a prebuilt binary baked into the Docker build-image
  to a vendored source snapshot (android/gl4es-src/) compiled from
  source at APK build time via CMake add_subdirectory(), patched through
  a new android/gl4es-patches/ (mirrors the existing engine-patches/
  pattern). This was needed to track down and fix a bug hit while
  building the menu: gl4es's fixed-pipeline emulation (fpe.c) was
  unconditionally substituting its own shader onto the menu's draw call
  (fpe_ReleventState() always sets alphafunc to a nonzero sentinel, so
  its fpe_IsEmpty() check could never see the state as empty), making
  the menu quad show the game's own rendering instead of its own
  content. Fixed by routing the menu's blit through a real
  glBlitFramebuffer() call instead of a shader-based draw, which gl4es's
  fpe.c has nothing to intercept - documented in README.md's new
  "Debugging notes" section.
- Renumber android/engine-patches/ to close the gap left by removing an
  unrelated diagnostic-only patch, and strip investigation-journal
  comments and dead diagnostic code (temporary tracing, env-var probes)
  left over from finding the bug above.
- Restructure README.md into numbered sections, document every
  engine/gl4es patch, add Android Studio dev/testing-cycle instructions,
  and generalize Quest-specific wording to any OpenXR headset. Update
  NOTICE.txt to match (gl4es is now vendored/patched source, not a
  prebuilt binary; add the OpenXR-SDK loader).

android/gl4es-src/src/egl/egl.h

@@ -0,0 +1,59 @@
+#ifndef _EGL_EGL_H_
+#define _EGL_EGL_H_
+
+#ifdef NOEGL
+# error Building EGL wrapper without EGL
+#endif
+
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+EGLint gl4es_eglGetError(void);
+EGLDisplay gl4es_eglGetDisplay(EGLNativeDisplayType display_id);
+EGLBoolean gl4es_eglInitialize(EGLDisplay dpy, EGLint *major, EGLint *minor);
+EGLBoolean gl4es_eglTerminate(EGLDisplay dpy);
+const char * gl4es_eglQueryString(EGLDisplay dpy, EGLint name);
+EGLBoolean gl4es_eglGetConfigs(EGLDisplay dpy, EGLConfig *configs, EGLint config_size, EGLint *num_config);
+EGLBoolean gl4es_eglChooseConfig(EGLDisplay dpy, const EGLint *attrib_list, EGLConfig *configs, EGLint config_size, EGLint *num_config);
+EGLBoolean gl4es_eglGetConfigAttrib(EGLDisplay dpy, EGLConfig config, EGLint attribute, EGLint *value);
+
+EGLSurface gl4es_eglCreateWindowSurface(EGLDisplay dpy, EGLConfig config, EGLNativeWindowType win, const EGLint *attrib_list);
+EGLSurface gl4es_eglCreatePbufferSurface(EGLDisplay dpy, EGLConfig config, const EGLint *attrib_list);
+EGLSurface gl4es_eglCreatePixmapSurface(EGLDisplay dpy, EGLConfig config, EGLNativePixmapType pixmap, const EGLint *attrib_list);
+EGLBoolean gl4es_eglDestroySurface(EGLDisplay dpy, EGLSurface surface);
+EGLBoolean gl4es_eglQuerySurface(EGLDisplay dpy, EGLSurface surface, EGLint attribute, EGLint *value);
+EGLBoolean gl4es_eglBindAPI(EGLenum api);
+EGLenum gl4es_eglQueryAPI(void);
+
+EGLBoolean gl4es_eglWaitClient(void);
+EGLBoolean gl4es_eglReleaseThread(void);
+EGLSurface gl4es_eglCreatePbufferFromClientBuffer(EGLDisplay dpy, EGLenum buftype, EGLClientBuffer buffer, EGLConfig config, const EGLint *attrib_list);
+EGLBoolean gl4es_eglSurfaceAttrib(EGLDisplay dpy, EGLSurface surface, EGLint attribute, EGLint value);
+EGLBoolean gl4es_eglBindTexImage(EGLDisplay dpy, EGLSurface surface, EGLint buffer);
+EGLBoolean gl4es_eglReleaseTexImage(EGLDisplay dpy, EGLSurface surface, EGLint buffer);
+EGLBoolean gl4es_eglSwapInterval(EGLDisplay dpy, EGLint interval);
+EGLContext gl4es_eglCreateContext(EGLDisplay dpy, EGLConfig config, EGLContext share_context, const EGLint *attrib_list);
+EGLBoolean gl4es_eglDestroyContext(EGLDisplay dpy, EGLContext ctx);
+EGLBoolean gl4es_eglMakeCurrent(EGLDisplay dpy, EGLSurface draw, EGLSurface read, EGLContext ctx);
+EGLContext gl4es_eglGetCurrentContext(void);
+EGLSurface gl4es_eglGetCurrentSurface(EGLint readdraw);
+EGLDisplay gl4es_eglGetCurrentDisplay(void);
+EGLDisplay gl4es_eglGetPlatformDisplay(EGLenum platform, void *native_display, const EGLAttrib *attrib_list);
+EGLBoolean gl4es_eglQueryContext(EGLDisplay dpy, EGLContext ctx, EGLint attribute, EGLint *value);
+EGLBoolean gl4es_eglWaitGL(void);
+EGLBoolean gl4es_eglWaitNative(EGLint engine);
+EGLBoolean gl4es_eglSwapBuffers(EGLDisplay dpy, EGLSurface surface);
+EGLBoolean gl4es_eglCopyBuffers(EGLDisplay dpy, EGLSurface surface, EGLNativePixmapType target);
+void* gl4es_eglGetProcAddress(const char *name);
+
+EGLSyncKHR gl4es_eglCreateSyncKHR(EGLDisplay dpy, EGLenum type, const EGLint *attrib_list);
+EGLint gl4es_eglClientWaitSyncKHR(EGLDisplay dpy, EGLSyncKHR sync, EGLint flags, EGLTimeKHR timeout);
+
+// Undocumented libmali internals, needed for ODROID Go Ultra
+NativePixmapType gl4es_egl_create_pixmap_ID_mapping(void *pixmap);
+NativePixmapType gl4es_egl_destroy_pixmap_ID_mapping(int id);
+
+#endif // _EGL_EGL_H
+