test(wallets): wait for async ongoing balance refresh

[mariohd]

Context

Six wallet integration tests (#update, #get, #get_all on both spec/integration/wallets_spec.rb and spec/integration/customers/wallets_spec.rb) fail in CI with expected: "10.0", got: "0.0" on credits_ongoing_balance.

balance_cents is updated synchronously when the wallet transaction settles, but ongoing_balance_cents / credits_ongoing_balance are refreshed by an async RefreshWalletJob. The existing wait_for_balance_update only polls until balance_cents == 2000, so the assertions can run before the ongoing refresh has landed and the wallet still reports 0.0 for the ongoing fields.

Fix

Adds a second wait inside assert_wallet_attributes_with_updated_balance that re-fetches the wallet until ongoing_balance_cents matches the expected value before asserting. The expected value is read from the optional ongoing_balance_cents override (default 2000), so tests that pass a custom override continue to drive the wait correctly.

expected_ongoing_balance_cents = attributes.fetch(:ongoing_balance_cents, 2000)
wait_until do
  wallet = client.wallets.get(wallet.lago_id)   # client.customers.wallets.get(...) in the nested file
  wallet.ongoing_balance_cents == expected_ongoing_balance_cents
end

Same shape applied to both the top-level (wallets_spec.rb) and customer-scoped (customers/wallets_spec.rb) helpers.

Tests

docker compose exec client bundle exec rspec \
  spec/integration/wallets_spec.rb \
  spec/integration/customers/wallets_spec.rb

All ten previously-failing examples pass; no regressions in the surrounding suites. The #destroy flake that occasionally surfaces when the two files run back-to-back is unrelated (HTTP 409 from leftover Lago state), passes in isolation, and was already green before this branch.

[mariohd]

Closed in favor of #357