ensure that there is at least one leading dot-slash at the beginning.

import { assertEquals } from "jsr:@std/assert"

// aliasing our functions for brevity
const eq = assertEquals, fn = ensureStartDotSlash

eq(fn("a/b.zip"), "./a/b.zip")
eq(fn(".///../a/b.zip/"), ".///../a/b.zip/")
eq(fn("///../a/b.zip/"), ".///../a/b.zip/")
eq(fn("file:///a/b.zip//c.txt"), "./file:///a/b.zip//c.txt")