The on-screen window capture is composited from the desktop framebuffer, so it
already includes the GL 3D viewport as currently shown (model in the editor,
toolpaths in Preview). The offscreen render_thumbnail path only ever drew the
model GLVolumeCollection — never the gcode toolpaths — and produced a blank image
after slicing because the app switches to the Preview panel. Rather than maintain a
second, more limited capture method, remove it entirely.
Removes the JSON-RPC method, IUiBackend/WxUiBackend implementation, dispatcher
route + capability entry, the now-dead opt_int/thumbnail_to_wximage helpers and
ThumbnailData include, the mock override + unit test, and the Python
screenshot_3d client method. Docs updated accordingly.
Blitting from the MainFrame's own wxClientDC clips out child HWNDs, so all of
OrcaSlicer's custom child-window controls (sidebar buttons/combos/panels) and the
GL canvas came back as uninitialized black bitmap memory. Read the window's
on-screen rectangle from the DWM-composited desktop via wxScreenDC instead, which
includes every child window, the OpenGL surface, and ImGui overlays.
Document the visible/unobscured requirement and the HiDPI logical-vs-physical
pixel caveat; clarify how screenshot.viewport3d differs and why it stays.
