Barometer

• Fields t, p (2 cols), static pressure Pa. p > 0 everywhere (global 95124–98517 Pa). Pressure is quantized to exact 1/128 Pa (a display artifact, far below the ~tens-of-Pa noise).
• MS5611 samples at 20 Hz nominal (median dt 0.05 s); delivered ~18 Hz because of recurring single-sample dropouts (gaps to ~0.6 s). Model dropout, not a fixed step.
• Support copies on mars_4/mars_8 are time-supersets.
• T_pximu_pxbaro is identity (Calibration).