fix(sim): rebuild the six film-sim color matrices to match the stock looks

Provia/Velvia/Astia/Classic Chrome/Classic Neg/Acros each get their own
primaries+cross-talk matrix measured against the pipeline, plus a split-tone
stage (shadow/highlight tint uniforms) for Classic Chrome's teal and Classic
Neg's green-cyan shadows vs warm highlights.

src/utils/toneShader.ts

@@ -1,4 +1,4 @@
-import { ColorAdjustments } from '../types';
+import { BaseFilter, ColorAdjustments } from '../types';
 
 // Tone-domain adjustments (Fuji-style Dynamic Range + Highlight/Shadow).
 // SkSL runtime effect over a child image shader.
@@ -28,13 +28,26 @@ import { ColorAdjustments } from '../types';
 // vib - vibrance -1..1: chroma-masked saturation. It rides along in this shader
 //       (rather than the colour matrix) because it needs per-pixel chroma:
 //       already-vivid pixels move least, so skins/skies deepen without the neon
-//       clip a plain Saturation boost causes. All-zero still = no pass.
+//       clip a plain Saturation boost causes.
+// shT/hlT - split tone (per-channel RGB bias, -1..1 each): a fixed cast applied
+//       to the shadows and/or the highlights only. A 4x5 colour matrix cannot do
+//       this — it is one linear map, so any cast it applies must also hit the
+//       midtones and the opposite end. Classic Neg wants green/cyan shadows with
+//       warm highlights at once, so the stock ships these values and the pass
+//       stays active for it even when every user knob is 0. All-zero still = no
+//       pass.
 export const TONE_SKSL = `
 uniform shader src;
 uniform float dr;
 uniform float hl;
 uniform float sh;
 uniform float vib;
+uniform float shTr;
+uniform float shTg;
+uniform float shTb;
+uniform float hlTr;
+uniform float hlTg;
+uniform float hlTb;
 vec4 main(vec2 xy) {
   vec4 c = src.eval(xy);
   vec3 rgb = clamp(c.rgb, 0.0, 1.0);
@@ -52,6 +65,10 @@ vec4 main(vec2 xy) {
   // cannot blow a dark saturated colour out to white.
   float cg = clamp(o / max(t, 0.0004), 0.55, 1.35);
   rgb = clamp(vec3(o) + (rgb - vec3(t)) * cg, 0.0, 1.0);
+  // Split tone (stock look): the shadows and the highlights may each carry
+  // their own tint, so the two ends of the curve can drift opposite ways
+  // (Classic Neg: green-cyan darks, warm brights) without touching mid-greys.
+  rgb = clamp(rgb + vec3(shTr, shTg, shTb) * shMask + vec3(hlTr, hlTg, hlTb) * hlMask, 0.0, 1.0);
   // Vibrance: push the LESS-saturated pixels harder than the vivid ones.
   float l2 = dot(rgb, vec3(0.2126, 0.7152, 0.0722));
   float mx = max(max(rgb.r, rgb.g), rgb.b);
@@ -68,17 +85,49 @@ export interface ToneUniforms {
   hl: number; // -1..1 (adjustments.highlight / 10)
   sh: number; // -1..1 (adjustments.shadow / 10)
   vib: number; // -1..1 (adjustments.vibrance / 10)
+  shT: [number, number, number]; // shadow split-tone RGB bias, -1..1
+  hlT: [number, number, number]; // highlight split-tone RGB bias, -1..1
 }
 
-export function getToneUniforms(adj: ColorAdjustments): ToneUniforms {
+// Per-stock tone pass. Fuji's Classic stocks are not a plain colour matrix:
+// Classic Neg splits its tone (green-cyan darks / warm brights) and Classic
+// Chrome crushes the shadows hard while muting colour. Those two parts live
+// here instead of in the 4x5 matrix, which cannot move one end of the curve
+// without also moving the other.
+const FILM_TONE: Partial<Record<BaseFilter, Partial<ToneUniforms>>> = {
+  'classic-chrome': { sh: -0.28 },
+  'classic-neg': { shT: [-0.018, 0.009, 0.013], hlT: [0.024, 0.008, -0.012] },
+};
+
+export function getToneUniforms(adj: ColorAdjustments, baseFilter?: BaseFilter): ToneUniforms {
   const drRaw = adj.dynamicRange ?? 'auto';
   const dr = drRaw === 'auto' || drRaw === 100 ? 0 : (drRaw - 100) / 300;
   const hl = Math.max(-1, Math.min(1, (adj.highlight ?? 0) / 10));
   const sh = Math.max(-1, Math.min(1, (adj.shadow ?? 0) / 10));
   const vib = Math.max(-1, Math.min(1, (adj.vibrance ?? 0) / 10));
-  return { dr, hl, sh, vib };
+  const film = (baseFilter && FILM_TONE[baseFilter]) || {};
+  const shT: [number, number, number] = film.shT ?? [0, 0, 0];
+  const hlT: [number, number, number] = film.hlT ?? [0, 0, 0];
+  return { dr, hl: hl + (film.hl ?? 0), sh: sh + (film.sh ?? 0), vib, shT, hlT };
+}
+
+// Flat uniform buffer for `makeShaderWithChildren` / `<Shader uniforms>` — the
+// order must match TONE_SKSL's declarations.
+export function toneUniformArray(u: ToneUniforms): number[] {
+  return [u.dr, u.hl, u.sh, u.vib, u.shT[0], u.shT[1], u.shT[2], u.hlT[0], u.hlT[1], u.hlT[2]];
 }
 
 export function toneIsActive(u: ToneUniforms): boolean {
-  return u.dr !== 0 || u.hl !== 0 || u.sh !== 0 || u.vib !== 0;
+  return (
+    u.dr !== 0 ||
+    u.hl !== 0 ||
+    u.sh !== 0 ||
+    u.vib !== 0 ||
+    u.shT[0] !== 0 ||
+    u.shT[1] !== 0 ||
+    u.shT[2] !== 0 ||
+    u.hlT[0] !== 0 ||
+    u.hlT[1] !== 0 ||
+    u.hlT[2] !== 0
+  );
 }