Boot tag flips from qwen3.8-distilled-heretic:9b to nuextract3:4b (verified
live: per-request routing already serves every registered tag; the boot tag
only decides which model is resident at start, so the first request after a
swap pays the load cost). FLM_CTX_LEN=-1 drops the global --ctx-len override
so each pack loads with its own trained context (nuextract3 32768, gemma4
131072).