Web mode #26

Idk how tf this might work, I just know I want it. An agent running on, like, a VPS should be able to go install .../thresh, configure it, then run a command to get a nice web UI going on localhost (by default) that shows their human all the work they've done in a nice reviewable way where they can leave comments and such. I'm thinking somewhat similar to how https://pulls.review looks, using diffs.com, nice coloured phosphor duotone icons, and so on, but maybe without LLM-powered change groups and orderings and such. I think the abridging is already cooler than what pulls.review has. Maybe the grouping and ordering would be nice, but later.