This adds a set of Wasm convenience functions to ease memory management. These are all prefixed with `ghostty_wasm` and are documented as part of the standard Doxygen docs. I also added a very simple single-page HTML example that demonstrates how to use the Wasm module for key encoding. This also adds a bunch of safety checks to the C API to verify that valid values are actually passed to the function. This is an easy to hit bug. **AI disclosure:** The example is AI-written with Amp. I read through all the code and understand it but I can't claim there isn't a better way, I'm far from a JS expert. It is simple and works currently though. Happy to see improvements if anyone wants to contribute.