[Ticket]: Expose the server-configured max API-key expiry

## Type

Feature

## Summary

The console hardcodes a conservative MAX_KEY_EXPIRY_DAYS = 89 because the real ceiling is not readable over RPC.

## Intent

Console UI/UX revamp epic: https://github.com/ADORSYS-GIS/converse-frontends/issues/368 — the console cuts every surface that fakes missing backend data; this ticket is the backend contract needed to restore the surface honestly.

## Acceptance Criteria

- Contract available over the authz-rpc / usage query path the console consumes.
- Console follow-up can render real values with no hardcoded nulls.

_Source of truth: https://github.com/ADORSYS-GIS/converse-frontends/issues/368_

Trace the authz-rpc or usage query path consumed by the console, and locate the server-side API-key expiry configuration behind the hardcoded 89-day ceiling. Confirm the response contract and any related tests before deciding where the configured maximum belongs; done means the query exposes the real ceiling for the console follow-up without a hardcoded fallback.

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