feat(viz): mesh_viewer — componente 3D con FBO + Lambert headlight

Compila/cachea por id un programa GLSL (vertex+fragment) con
iluminacion Lambert (luz=camara), gestiona Framebuffer cacheado por
id, dibuja MeshGpu con orbit camera, muestra via ImGui::Image y
maneja drag (mouse) + wheel (zoom). Wireframe opcional via
glPolygonMode.

gl_loader: añade glUniformMatrix4fv (proc requerido en Windows para
subir las matrices view/proj del mesh_viewer).

issue 0029

cpp/functions/gfx/gl_loader.cpp

@@ -31,6 +31,7 @@ PFNGLUNIFORM2FPROC           fn_glUniform2f           = nullptr;
 PFNGLUNIFORM3FPROC           fn_glUniform3f           = nullptr;
 PFNGLUNIFORM4FPROC           fn_glUniform4f           = nullptr;
 PFNGLUNIFORM4FVPROC          fn_glUniform4fv          = nullptr;
+PFNGLUNIFORMMATRIX4FVPROC    fn_glUniformMatrix4fv    = nullptr;
 PFNGLUSEPROGRAMPROC          fn_glUseProgram          = nullptr;
 PFNGLACTIVETEXTUREPROC       fn_glActiveTexture       = nullptr;
 PFNGLGENERATEMIPMAPPROC      fn_glGenerateMipmap      = nullptr;
@@ -82,6 +83,7 @@ bool gl_loader_init() {
     LOAD(glUniform3f);
     LOAD(glUniform4f);
     LOAD(glUniform4fv);
+    LOAD(glUniformMatrix4fv);
     LOAD(glUseProgram);
     LOAD(glActiveTexture);
     LOAD(glGenerateMipmap);