/price/:assetA/:assetB/history pools testnet and mainnet rows into one OHLCV series #208

src/api/rest.ts:160-170 queries price_aggregates on pair_key alone:

SELECT bucket, window, vwap, sdex_vwap, amm_vwap, volume, trade_count,
       open_price, close_price, high_price, low_price
  FROM price_aggregates
 WHERE pair_key = $1 AND window = $2
 ORDER BY bucket DESC
 LIMIT $3

price_aggregates is written per network, so on an instance where ENABLED_NETWORKS covers both chains the returned buckets interleave testnet and mainnet rows for the same pair_key. A caller gets one OHLCV series that is not a series of anything — and because the route takes no network parameter, there is no way to ask for the one they meant.

Same class as the /basket problem #181 is addressing on that route. A price with the wrong network is worse than no price.

Fix: filter on network, read it from req.network ?? activeNetwork the way /price/:assetA/:assetB and /prices/history already do, echo the answered network back in the response, and add NetworkQuery to the route's openapi.yaml entry plus the network field to its response schema. A test with rows for both networks at the same pair_key and bucket, asserting only one network's rows come back, is what proves it.

The README already describes this under "Still reading across both networks"; this issue is to close it rather than document it.

Found while reviewing #179, which correctly left network off this route's spec entry because the route genuinely ignores it today.