The first /vibe hit cold-loaded CLAP (~16s) with the UI stuck on 'searching…',
reading as hung. Now serve.py warms the model in a daemon thread at startup (when
semantics_embeds.npz is present) so the first query is instant; the client shows
'first search loads the model, ~15s' on a cold start and aborts after 90s with a
retry hint instead of spinning forever.