refactor: replace io-ts with zod

backend/src/utils/zColor.ts

@@ -0,0 +1,15 @@
+import z from "zod";
+import { parseColor } from "./parseColor";
+import { rgbToInt } from "./rgbToInt";
+
+export const zColor = z.string().transform((val, ctx) => {
+  const parsedColor = parseColor(val);
+  if (parsedColor == null) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: "Invalid color",
+    });
+    return z.NEVER;
+  }
+  return rgbToInt(parsedColor);
+});