fix: add composite index for summing payments

[rolznz]

fixes https://github.com/getAlby/nostr-wallet-connect/pull/140 improves performance of query to sum payments in current budget period

[bumi]

Will this update the current DB, too? is this a migration? I still think we need a combined index on app_id, created_at, preimage for that main query. and we might want to include the amount to easily calculate - then PG can get everything from the index and does not need to look into the rows

[rolznz]

@bumi it's an automatic migration.

So we create an index for all 4 fields, should we still add indexes for the individual columns too?

[rolznz]

@bumi updated

[rolznz]

Replaced by https://github.com/getAlby/nostr-wallet-connect/pull/148