[filipkunc]

What changed

• add a desktop-only --smoke-test mode that creates an OpenGL context, verifies OpenGL 3.3 Core, renders one frame, finishes GPU work, and fails on GL errors
• run that smoke test in the Linux GitHub Actions job under Xvfb with Mesa software rendering
• label the native CI matrix explicitly as Desktop OpenGL 3.3
• document the local smoke-test command
• make the adjacent Monaco keyboard-isolation test deterministic by testing one real keypress instead of a timing-sensitive synthetic typing stream

Why

The existing desktop CI already compiled and linked the OpenGL 3.3 path on Linux, macOS, and Windows, but it did not start the executable. This adds deterministic runtime coverage for context creation, shader/resource initialization, and one rendered frame.

The first PR run also exposed an unrelated pre-existing browser-test flake: under CI load, Monaco dropped different characters from a 19-character synthetic typing stream. The focused test now initializes the prefix through the editor API and sends one real browser keypress, preserving keyboard-isolation coverage without timing sensitivity.

Validation

• cmake --build --preset desktop-release --parallel
• ctest --preset desktop-release — 142/142 passed
• ./MeshMakerWebGL2 --smoke-test — passed with an OpenGL 3.3 Core context on NVIDIA 610.57.04
• cmake --preset webgl && cmake --build --preset webgl --parallel — passed
• focused Monaco test repeated 10 times — 10/10 passed
• complete Script Editor Playwright spec — 22/22 passed
• frontend lint — 0 errors (2 pre-existing warnings)
• GitHub Actions run 32053129813 — all jobs passed