Absolute camera orientation in degrees: azimuth horizontal (normalized
into 0-360), elevation from the horizon (clamped just inside ±90°, where
the view matrix degenerates). The target and the orbit distance are kept —
this rotates the camera, it does not reframe; use FIT_TO_VIEW for that.
zoom is NOT applied. It has no defined meaning on this side (factor?
distance? relative to what?), and the viewer deliberately ignores it rather
than guessing — see #2934. Treat it as reserved.
Payload types for each inbound command