Desktop panel fit.\n\n- Lowered the right analytical panel lane so it sits closer to the season/timeline shelf.\n- Tightened the shelf gutter from 12px to 6px while preserving separation.\n- Added smoke coverage that fails if side panels leave too much empty space above the shelf.\n- Built artifact SHA-256: 6661732edebbdb76b83b99e826f84693a3b694dd0e2fedf407ccbfcdf02f96e5