next.js

be481241 - [test debug] Tag probes with the dev server port and add a hydration stall — DO NOT MERGE

[test debug] Tag probes with the dev server port and add a hydration stall — DO NOT MERGE The 30x run went red on two dev shards, but eight jest workers share one log, so no single test's trail can be read out of it. Prefix every probe with location.port, which is unique per test file, to make the CI log demuxable. The stall knob is for the local repro attempt and is a no-op unless BBH_STALL is set.