Enhances the README by adding a gallery showcasing OMath's capabilities,
providing a clearer installation guide, and improving usage examples
to facilitate easier adoption.
Also restructures the navigation for better user experience.
Updates the README to use local image links instead of Imgur links for the showcase section.
This improves the project's resilience against external link rot and
ensures the images remain accessible even if Imgur experiences issues.
Replaces the project banner in the README with a dedicated logo.
This change simplifies the banner implementation and improves maintainability
by using a local image file instead of referencing an external URL.
