Enrich response keys and add token follow-ups

[galetahub]

Adds missing result keys and cross-engine token patterns to response.md.

• New result keys: immersive_product, lens, events, autocomplete, tripadvisor, product-detail engines
• Trends: result key now mapped per data_type (TIMESERIES/GEO_MAP/RELATED_*)
• New "Token follow-ups" section: shopping→immersive, google→ai_overview, maps→maps_reviews (with ai_overview ~1min token expiry)