Bridge Module
The main-process half of Issie's renderer bridge. Every operation the renderer is allowed to ask the operating system for is registered here, as a named channel with a fixed shape. The renderer half is src/Preload/preload.js, and the two are meant to be read together: nothing should be exposed there that is not answered here, and nothing answered here should take a request general enough to stand in for `require`. Handlers use event.returnValue, the synchronous form, because the renderer's file wrappers return values from inside Elmish update and cannot await. get-user-data in Main.fs already worked this way before any of this existed.