Run wasm-opt explicitly as part of tools/release.

There are no prebuilt binaries for M1, so wasm-pack just skips it. However you can manually install wasm-opt and run it, so let's do that.

Also:

Put the brotli compression back. I think it's good for us to put our best foot forward in the binary, so to speak.
Change "profiling" to "debug". There's no difference in file size between profiling and release. I have no idea what it's supposed to change. I figure if we're going to have a debug build let's at lease maximize its utility. With wasm-opt and brotli, the difference is only ~50% (the debug build is 300k), so it seems reasonable to expose to users. Maybe it will be a better debugging experience.

rocicorp / repc