Shot reel: rendered clip+chart video with audio-calibrated sync

[AlexNly]

After each camera shot MATEbot now:

1. Auto-calibrates the sync offset (calibrate.py): the pump's audio onset in the clip is aligned with the pump command (tp) in the shot data, giving the exact per-shot offset - no manual /vsync. Falls back to MATEBOT_CAMERA_OFFSET when audio is unusable.
2. Renders a shot reel (render.py): portrait mp4, clip on top, chart below animated by a wipe + playhead that track the x axis pixel-exactly (geometry from matplotlib via plot.render_shot_chart). Pure ffmpeg animation, single pass. Sent to the chat via new Messenger.send_video (telegram + discord + text fallback). MATEBOT_REEL=0 disables.

Verified on a real shot: audio calibration measured +0.6s where the default guess was -1.0s; playhead crosses each axis tick exactly on time.