Document liquidity fields (volume, volume_24h, open_interest, max_bet coverage) on /odds endpoint

[Mlaz-code]

Summary

The /api/v1/odds response surfaces several liquidity-adjacent fields that are either undocumented or under-documented. A customer (High Summit Holdings, mid-trial-evaluation) asked about liquidity coverage today and Maya answered "we don't surface depth/size data" — which is wrong on three counts.

What's actually surfaced (verified in sharp-api-go/main.go:525-528 and :568-570)

Both JSON shapes carry these fields:

Field	Type	Source	Documented today?
volume	float	Exchanges (Polymarket, Kalshi, Novig)	❌ no
volume24h / volume_24h	float	Exchanges	❌ no
openInterest / open_interest	float	Exchanges	❌ no
max_bet	float	Pinnacle, SBObet (per adapters/pinnacle.py:2524 + adapters/sbobet.py:913)	⚠️ partial — docs say "Pinnacle only" but SBObet also writes it
exchange_token_id	string	Exchanges	❌ no

These are real liquidity signals — volume_24h + open_interest for exchanges is exactly the "depth of book" proxy that pre-match trading clients ask about; max_bet is the per-line wager ceiling. Customers are flying blind on coverage decisions because the docs imply liquidity isn't available at all.

What's NOT surfaced (correctly absent)

• Bid/ask order book depth (no traditional sportsbook exposes this in their public APIs)
• Pre-bet limit checks via API
• Real-time book-side suspension reasons (we emit odds:removed deltas but not the cause)

Action requested

1. Document volume, volume_24h, open_interest, exchange_token_id on /api/v1/odds field table (content/en/api-reference/odds.mdx). Note which books emit each.
2. Correct the max_bet line to mention SBObet alongside Pinnacle (currently says "Pinnacle only").
3. Add a Liquidity & Limits section to concepts/ explaining what we DO and DO NOT surface, so future customer questions land on a docs page instead of generating Crisp follow-ups. Reference from /api/v1/odds field table.

Related customer touchpoint

• 2026-05-19 High Summit Holdings Crisp session_e256fef6 — answered (incorrectly) that we don't surface liquidity. Follow-up correction sent.

Acceptance

• docs.sharpapi.io/api-reference/odds shows the 4 exchange liquidity fields and the corrected max_bet description.
• A concepts/liquidity.mdx page exists explaining the boundary between what we surface and what upstream books don't expose.