Adds a new content rewrite rule to strip image URL query parameters from blurred images.
This addresses issues with sites like Belgian national news that use blurry placeholder images which get replaced with high-quality versions, allowing Miniflux to fetch the original images instead of the placeholders.
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
