db: app depends on non-existent dex_ex_summary table

[conorsch]

While reviewing #125, I noticed a logged exception about the dex_ex_summary table missing:

✓ Compiled /trade/[baseSymbol]/[quoteSymbol] in 1ms (539 modules)
 ⨯ error: relation "dex_ex_summary" does not exist

That's because the app is currently connected to a "raw" CometBFT ABCI event database, not a pindexer database, which would have the dex_ex_summary. I reported this to @grod220 and he confirmed that the migration to using pindexer-only queries is nearly complete, part of the overhaul described in #36.

Filing this now so that post db cutover we confirm the error is no longer occurring.

[conorsch]

This issue is still occuring on the testnet deployment, post cut-over to the new pindexer db in #128. But that's mostly due to another schema change, which is best tracked in #132, so closing this issue as duplicate.