Fix duplicate rows in /coins if multiple reward pool accounts (#577)

- I accidentally created a non-ATA account on the authority of PHUTURES
- Later created the ATA
- `/v1/coins` was giving duplicate rows for PHUTURES
- Fix by only selecting earliest-created account for that owner - as a
proxy for the ATA, assuming we'd create it as part of the reward pool
creation process.
- But technically the PHUTURES response is still showing the wrong
account (since I created the non-ATA before the ATA). Not a huge issue
bc we don't use that value anywhere. But maybe I can just delete that
row for this case?

Tested on prod

Author: dharit-tan

api/v1_coins.go

@@ -202,9 +202,13 @@ const sharedSelectCoinSql = `
 			ON artist_coin_pools.base_mint = artist_coins.mint
 		LEFT JOIN sol_reward_manager_inits
 			ON sol_reward_manager_inits.mint = artist_coins.mint
-		LEFT JOIN sol_token_account_balances AS reward_pool
-			ON reward_pool.owner = sol_reward_manager_inits.authority
-			AND reward_pool.account != sol_reward_manager_inits.token_source
+		LEFT JOIN LATERAL (
+			SELECT * FROM sol_token_account_balances
+			WHERE owner = sol_reward_manager_inits.authority
+			AND account != sol_reward_manager_inits.token_source
+			ORDER BY created_at ASC
+			LIMIT 1
+		) AS reward_pool ON true
 `
 
 type GetArtistCoinsQueryParams struct {