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.

src/modules/investments/operations/operations.api.ts

@@ -2,10 +2,7 @@
 export { BrokerageOperationDto } from './presentation/brokerage-operation.dto';
 export { BrokerageOperationsService } from './application/brokerage-operations.service';
 
-export {
-  operationIntervals,
-  type OperationInterval,
-} from './domain/operations-sync-plan';
+export type { OperationInterval } from './domain/operations-sync-plan';
 
 export { operationCategories } from './presentation/brokerage-operation.dto';
 export { BrokerageOperationsSyncService } from './application/brokerage-operations-sync.service';