Finish dark.ts initial port and restructure files to get ready for build script

Build script currently fails to type check. Not sure whats going on. Will fix in the morning.

Co-authored-by: Nate Butler <nate@zed.dev>

styles/utils/color.ts

@@ -0,0 +1,44 @@
+import chroma, { Scale } from "chroma-js";
+
+export type Color = string;
+export type ColorRampStep = { value: Color; type: "color"; step: number };
+export type ColorRamp = {
+  [index: number]: ColorRampStep;
+};
+
+export function colorRamp(
+  color: Color | [Color, Color],
+  options?: { steps?: number; increment?: number }
+): ColorRamp {
+  let scale: Scale;
+  if (Array.isArray(color)) {
+    const [startColor, endColor] = color;
+    scale = chroma.scale([startColor, endColor]);
+  } else {
+    let hue = Math.round(chroma(color).hsl()[0]);
+    let startColor = chroma.hsl(hue, 0.88, 0.96);
+    let endColor = chroma.hsl(hue, 0.68, 0.32);
+    scale = chroma
+      .scale([startColor, color, endColor])
+      .domain([0, 0.5, 1])
+      .mode("hsl")
+      .gamma(1)
+      .correctLightness(true)
+      .padding([0, 0.15]);
+  }
+
+  const ramp: ColorRamp = {};
+  const steps = options?.steps || 10;
+  const increment = options?.increment || 100;
+
+  scale.colors(steps, "hex").forEach((color, ix) => {
+    const step = ix * increment;
+    ramp[step] = {
+      value: color,
+      step,
+      type: "color",
+    };
+  });
+
+  return ramp;
+}