Grow cameras see the plants: a saved camera profile per station (exposure, white balance), full-res stills cropped to the box, colour correction under grow light #584

Owner 2026-10-26: "the cameras are having a really hard time seeing the plants."

Probed 22:15Z (snapshots from :8080 and :8081):

• Overhead (eMeet C960, :8081) looks at the top of the light panel. The plants are under it, so it sees a blown-out glow. This is placement, not settings.
• Side (XWF-1080P, :8080), auto exposure meters on the bright box, which comes out as a white blob on blue. By hand I set auto_exposure=1, exposure_time_absolute=180, backlight_compensation=0, white_balance_automatic=0, white_balance_temperature=6500. Now the inside of the dome and the tray show. The box is still only ~20% of a 640×360 frame. These settings are lost on a re-plug or reboot.
• The grow light is blue/violet only, so colour is never true under it. Green (the plants) reflects little of it.

Done when:

1. A camera profile per station camera, persisted in the stations config and re-applied by so101-camera on every start or re-plug (a udev hook or ExecStartPre v4l2-ctl): exposure mode and time, white balance, gain, and focus. /admin gets a "Tune" panel with live preview, sliders and Save.
2. Stills use full resolution: grab 1920×1080 (XWF supports it; the stream stays 640×360 to keep the Pi light) and crop to a region the owner draws once (the box), so the timelapse and canopy chart see the plants, not the room.
3. Colour under grow light: a per-camera colour correction for stills (gray-world, or a calibration shot of a white card under the grow light), labelled "corrected". Optionally a photo light: if a white LED switch exists (#582's Switch interface), turn it on for 2 s around each still while the grow light is briefly dimmed or left on. Only via the schedule's driver, never by cutting USB.
4. A setup hint on the grow card when the plants aren't visible (the region is mostly blown-out or black): "Camera can't see the plants: move it inside or beside the box, below the light."
5. Tests: the profile round-trip (config → the v4l2-ctl args the launcher runs); the crop math; the correction on a fixture image; the visibility check flags an overexposed fixture.

Owner-chosen settings 2026-10-26 (keep these as the saved profiles' defaults):

• Overhead, eMeet C960 (:8081): brightness=115 contrast=120 saturation=150 (owner: "saturation up a little … looked good").
• Side, XWF-1080P (:8080): auto exposure and auto white balance, backlight_compensation=1 (owner: "camera 1 is decent").

Both are set live by hand and lost on a re-plug or reboot until this issue persists them.