`cacheBustingQueryParam ` breaks relative paths when `manifestRelativePaths = true`

[jchafik]

When specifying cacheBustingQueryParam, the private cacheBusting is invoked, unintentionally prefixing the resulting string with /. This disrupts relative URLs, causing incorrect path resolution.

favicons/src/platforms/base.ts

Line 101 in a4e4367

protected cacheBusting(path: string): string {

    const url = new URL(path, "https://cache.busting");
    url.searchParams.set(paramParts[0], paramParts.slice(1).join("="));
    return url.origin === "https://cache.busting"
      ? url.pathname + url.search
      : url.toString();

You could potentially add something like:

protected cacheBusting(path: string): string {
  if (typeof this.options.cacheBustingQueryParam !== "string") {
    return path;
  }

  const paramParts = this.options.cacheBustingQueryParam.split("=");

  if (paramParts.length === 1) {
    return path;
  }

  const url = new URL(path, "https://cache.busting");
  url.searchParams.set(paramParts[0], paramParts.slice(1).join("="));

  if (url.origin !== "https://cache.busting") {
    return url.toString();
  }

  const resolvedPath = url.pathname + url.search;

  // Preserve relative paths
  if (!path.startsWith("/") && resolvedPath.startsWith("/")) {
    return resolvedPath.substring(1);
  }

  return resolvedPath;
}