Add bare-minimum extension-reaper-macos REAPER extension skeleton

C/C++ extension built directly against the vendored Cockos reaper-sdk
headers (no Rust/reaper-rs wrapper layer). Loads, registers a test
action, and confirms via REAPER's console — confirmed working in
REAPER 2026-07-15.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

extension-reaper-macos/vendor/reaper-sdk/WDL/lice/lice_gl_ctx.h

@@ -0,0 +1,27 @@
+#ifndef _GL_CTX_
+#define _GL_CTX_
+
+#include "lice.h"
+
+#define GLEW_STATIC
+#include "glew/include/gl/glew.h"
+#include "glew/include/gl/wglew.h"
+#include "glew/include/gl/wglext.h"
+
+// GL context functions
+// opening and managing GL context is handled behind the scenes
+
+
+bool LICE_GL_IsValid(); // GL context is initialized (will be lazy initialized on first call) and valid
+
+HWND LICE_GL_GetWindow(); // Get the window that owns the GL context (one per process)
+
+void LICE_GL_CloseCtx();  // Something failed, turn off GL context forever so we don't keep failing
+
+GLUnurbsObj* LICE_GL_GetNurbsObj(int linetol=8);  // linetol = maximum number of straight-line pixels
+
+// facility for associating a glyph with a texture
+GLuint LICE_GL_GetTexFromGlyph(const unsigned char* glyph, int glyph_w, int glyph_h); 
+void LICE_GL_ClearTex();
+
+#endif