feat(langgraph): show per-passenger-type fares in the flight LIST

When a trip mixes passenger types (adult/child/infant), the list showed one averaged 'price × N' line — but an infant costs far less than an adult, so the average reads as wrong. Render each type's per-person fare on its own line ('👤 Adult · 1.81 USD') from the offer fact's fares breakdown, localized (digits + currency label) per locale. A single-type trip (lone adult, or N of the same type) keeps the compact '💰 price × N' line.

Verified live (Mashhad→Tehran, 1 adult + 1 infant, fa): adult + infant fares now shown separately in every offer row.

Co-Authored-By: Claude Opus 4.8 (1M context) noreply@anthropic.com