refactor!: support RUB only (WealthLedger/main#55)

Filter non-RUB data at ingest and collapse per-currency collections
into a single RUB Money. Drop currency from TbankPortfolioValuePoint,
remove NON_RUB_ACTIVITY and the screener currency filter.

BREAKING CHANGE: per-currency API fields replaced with single RUB Money.

test/openapi-contract.e2e-spec.ts

@@ -98,7 +98,7 @@ describe('OpenAPI contract (integration)', () => {
       expect.arrayContaining([
         'accountId',
         'period',
-        'totalsByCurrency',
+        'total',
         'calculatedAt',
         'bucketGranularity',
         'buckets',