Smart Route

Powers the homepage's single "tell me what you're thinking" input box (js/smart-router.js): given free text, figures out which Engine page best answers it (and any ticker mentioned), so a visitor doesn't need to already know XFINLAB has 11 separate tools.

js/smart-router.js tries its own fast regex/keyword pass first and only calls this endpoint when that's inconclusive -- this endpoint re-runs the same fast pass server-side (cheap, no harm) and falls back to an AI classification call only if that also comes up empty. See services/intent_router_service.py for the full design rationale.