Priority & interactive jobs

When we're iteratively experimenting with code, it is currently sometimes more convenient to get a proper shell on a server with the FPGA toolchain instead of using Polyphemus. It's just easier to run commands and see their output right there, immediately.

But we can do better. Polyphemus is pretty close (but not _quite_ capable enough) to support a workflow that simulates the experience of local development on your laptop while taking advantage of server-side tools, licenses, and speed. Here's what would be needed:

- [ ] A way to mark a job as "interactive" or having "high priority," so it jumps the line and runs immediately, even if there are other jobs currently going.
- [ ] An API to stream the log as it is produced. (This seems hard because we are currently let commands pipe directly to the filesystem, but we can fake it with polling or use inotify or whatever.)
- [ ] A CLI tool that submits the current directory as a new job, immediately starts streaming the log to the console, and exits when the job completes or fails.

(Expanded from #1.)

Start by breaking the issue into its three stated requirements: interactive or high-priority jobs, streamed logs, and a CLI for submitting the current directory. Done means the workflow supports immediate execution, visible log output while the job runs, and a CLI that exits when the job completes or fails.

Written by the indexing model from the issue text.