Replaced the `Logging` configuration in both `appsettings.json`
and `appsettings.Development.json` with Serilog, enabling
structured logging with configurable sinks and enrichment.
Added `DocumentOperatorSettings` to manage temporary files
and logging details. Introduced `RedisSettings` for Redis
integration, including connection string and cache settings.
Added `ApiKeySettings` to support tenant-specific API key
validation with detailed configuration for each tenant.
These changes improve logging, caching, and configuration
management for better maintainability and extensibility.
