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/integrations/tbank/tbank.api.ts

@@ -2,13 +2,14 @@
 export { InstrumentMetadataService } from './instrument-metadata.service';
 export {
   TbankAccessService,
-  type TbankConnectionContext,
+  type TbankSyncAttempt,
 } from './tbank-access.service';
 export {
   type TbankBond,
   type TbankCandle,
   type TbankCoupon,
   type TbankFundamentals,
+  type TbankLastPrice,
   type TbankShare,
 } from './tbank-market.types';
 export { TbankTokenService } from './tbank-token.service';