Extend the input single-view photograph into a complete 360-degree panorama. Projection: true equirectangular, covering 360 degrees horizontally and 180 degrees vertically, including the sky overhead and the ground below; left and right edges must join seamlessly into one continuous scene. Completion: extend the environment behind the camera plausibly (ground, walls, vegetation, sky, consistent light direction) with no repeated or broken areas. Keep: the subject appears exactly once, with its appearance, pose and relationship to surrounding objects unchanged, never mirrored or duplicated. Output at exactly a 2:1 aspect ratio, for example 2880x1440.
