MIME-Types and `Content-Encoding`s are off

[lishaduck]

Why

This is an enhancement becuase the game still works, but this would be a big server-side improvement.

The Plan

#### Tasks
- [ ] Give `.pkg` files the content type `application/octet-stream`
- [x] Use brotli and gzip compression

[lishaduck]

Hmmm. Content-Encoding should be automatic. I'll need to do further investigation.

[lishaduck]

Hmmm. Content-Encoding should be automatic. I'll need to do further investigation.

Aha! It only happens for files over 64 bytes, so only the wasm file was getting compressed.

[lishaduck]

Hmmm. It looks like the server is overwriting my custom content type for .pkg. I'll need to try a different approach later, but it isn't that important.