Selector Collision Finder

Grinds signatures from a pattern you supply, looking for one whose keccak hash starts with the same four bytes as your target. Searching runs in timed slices rather than one loop, because ten million keccak hashes in a tight loop freezes the tab long enough that the browser may kill it. When it fails it says something useful rather than nothing: there are 2^32 possible selectors, a random search needs roughly 4.3 billion attempts on average, and it reports the fraction of that space you actually covered along with how long a full search would take at your observed hash rate. The point is to show that collisions exist and are cheap enough to matter — a selector alone never proves which function is being called.