fix: prefer local text encoder API in api mode when available

fix: fallback to local text encoder API when remote URL times out

fix: HTTP readiness gate in _ensure_text_encoder_server

Switch to LLM2Vec 3.1 pair to fix Space 401 on gated Llama 3.0

Sync text encoder 3.0 fix and smoke checks

Switch LLM2Vec to Meta-Llama-3.1-8B-Instruct (accessible with current token)

Use mirrored LLM2Vec base model repo and env overrides

Add core kimodo package modules required by native demo