FX vignetting, LIGHT vibrance/saturation, reticle unlock

- 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.

src/utils/paramDefs.ts

@@ -60,7 +60,7 @@ export const PARAM_DEFS: {
     },
     {
       key: 'color',
-      label: 'COLOR',
+      label: 'SATURATION',
       min: -10,
       max: 10,
       step: 1,
@@ -69,6 +69,17 @@ export const PARAM_DEFS: {
       get: (a) => a.saturation,
       set: (v) => ({ saturation: v }),
     },
+    {
+      key: 'vibrance',
+      label: 'VIBRANCE',
+      min: -10,
+      max: 10,
+      step: 1,
+      defaultValue: 0,
+      display: sign,
+      get: (a) => a.vibrance ?? 0,
+      set: (v) => ({ vibrance: v }),
+    },
     {
       key: 'highlight',
       label: 'HIGHLIGHT',
@@ -172,5 +183,16 @@ export const PARAM_DEFS: {
       get: (a) => a.hdf ?? 0,
       set: (v) => ({ hdf: v }),
     },
+    {
+      key: 'vignette',
+      label: 'VIGNETTING',
+      min: 0,
+      max: 10,
+      step: 1,
+      defaultValue: 0,
+      display: String,
+      get: (a) => a.vignette ?? 0,
+      set: (v) => ({ vignette: v }),
+    },
   ],
 };