Public — no auth. THE canonical current price for a coin.

This is the single source of truth every other endpoint's price/spot field should agree with. Returns {"coin","price","source","ts","age_secs","note"}. 404 if the coin is unknown.

2026-07-14: was calling the SYNC HL SDK (_all_mids -> _get_info().all_mids()) directly on the event loop — the exact class of blocking call that froze the whole API for 40-88s. Now served from the shared off-loop mids cache.