This PR refactors the configuration parser, replacing the old parser implementation with a new, more structured approach that includes validation and improved organization.
Key changes:
- Complete rewrite of the configuration parser using a map-based structure with built-in validation
- Addition of comprehensive validator functions for configuration values
- Renamed numerous configuration getter methods for better consistency
Since go-webauthn v0.11.0, the backup eligibility flag is strictly validated, but Miniflux does not store this flag.
This workaround to set the flag based on the parsed response, and avoid "BackupEligible flag inconsistency detected during login validation" error.
See https://github.com/go-webauthn/webauthn/pull/240
