- FX: new VIGNETTING 0-10 control (chip + slider). Darkens the four
corners of the photo with a radial gradient whose radius is the photo
diagonal/2, so the falloff stays circular on any aspect. Applied in
preview (camera overlay, polaroid/wall window, plain library) and in
exportEngine pass 6b, always on the picture, never on the mat.
- LIGHT: new VIBRANCE -10..+10 (chroma-masked saturation in the tone
shader: vivid pixels move least). Renamed the existing saturation
control chip from COLOR to SATURATION - same param, clearer label.
- Fix: <Shader> takes a RuntimeEffect, not a gradient SkShader; the
preview vignette threw "Object is not a HostObject" when it got one.
Use the declarative <RadialGradient> child on the Rect instead.
- Preview: drop the "AE/AF LOCKED - TAP TO UNLOCK" banner; the lock
reticle is now itself the unlock touch target.