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.

src/modules/investments/instruments/stocks/application/get-stock-company.use-case.ts

@@ -70,16 +70,17 @@ export function metrics(
     // eslint-disable-next-line security/detect-object-injection -- Keys come from the fixed metric selection declared above.
     const value = values[key];
     const currency = values.currency?.toUpperCase() || null;
+    const rub = currency === 'RUB';
     return typeof value === 'number' &&
       Number.isFinite(value) &&
-      (unit !== 'money' || currency)
+      (unit !== 'money' || rub)
       ? [
           {
             key,
             value,
             unit,
             period,
-            currency: unit === 'money' ? currency : null,
+            currency: unit === 'money' ? 'RUB' : null,
           },
         ]
       : [];