Implement a log endpoint, allowing browser extension to write things to persistent log

[max-baz]

This could allow us to simplify debugging, by letting extension write errors and/or debug logs to persistent log.

[gotjoshua]

i'm on nixos chromium, and the extension generally works great, but does't manage to encrypt in some folders with additional keys configured. is there a way to check/watch the logs of the native host somehow (even without a fix via this issue)?