fix: harden auth and investment synchronization

Resolve A01-A10 and C01-C07 from the backend audit.
Preserve auth failures, forced candle reconciliation and forecast freshness.
Validate MOEX responses and nested HTTP errors; remove unused legacy paths.

Verified: 209 unit tests, 262 SQLite e2e tests on Linux, OpenAPI and durability.
Record the remaining macOS native SQLite abort in the audit.

test/tbank-operations-sync.e2e-spec.ts

@@ -42,7 +42,7 @@ describe('Request-driven operations synchronization (SQLite)', () => {
       TOKEN_ENCRYPTION_KEY: process.env.TOKEN_ENCRYPTION_KEY,
     }),
   );
-  const access = new TbankAccessService(prisma, tokens, upstream as never);
+  const access = new TbankAccessService(prisma, tokens);
   const logger = { event: jest.fn() };
   const createService = () =>
     new BrokerageOperationsSyncService(