F29: Export/import settings — gear icon in header opens settings popover,
export downloads all llm-* localStorage as JSON, import validates
and merges, both with toast feedback
F30: Inference history log — saves prompt/response/model/metrics to
llm-inference-log (capped 100 FIFO), searchable panel with replay
button, count badge in header toggle
F31: Factory reset — confirm dialog clears all llm-* localStorage keys,
resets all component state to defaults
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