Two bugs made a freshly-configured model unusable until a full restart on a
multi-engine node:

1. Name mismatch: list_models advertises a gguf's filename WITHOUT .gguf as an
   id, but get_all_allowed_identifiers only allowed the name WITH .gguf, so a
   request using the id from /v1/models was 404'd as "not an allowed model".
   Now the .gguf-stripped stem is allowed too.

2. Stale per-engine assignment: each engine's /v1/models is filtered by the
   assignment set fixed at startup, and secondary engines never re-read
   models.json — so an added/removed model didn't show up or route until
   restart. The front now watches models.json mtime, recomputes the
   assignment, updates its router, and pushes it to every engine via a new
   internal POST /internal/reload-config (re-reads models.json +
   set_assigned_models). /v1/models and routing now reflect add/remove live.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>