Switch fonts to SpaceGrotesk and SpaceMono with footer updates

[asphaltbuffet]

This pull request introduces several improvements across the build process, UI, and versioning system. The most significant changes include switching the UI fonts to open-source alternatives, enhancing the build pipeline to inject more detailed version metadata, and updating the application to display version information in the footer. Additionally, it removes proprietary font files and their licenses, further streamlining the project.

UI and Font Updates:

• Replaced proprietary "iA Writer" fonts with open-source "Space Grotesk" and "Space Mono" fonts in app.css, and updated CSS variables to use the new fonts. [1] [2]
• Removed the OFL.txt font license file for the "iA Writer" fonts, as they are no longer used.

Footer and Version Display:

• Added a new footer template (partial_footer.html) that displays the application version and Git commit, and included it in the main page layout. [1] [2]
• Added styles for the new footer in app.css.

Build and Versioning Enhancements:

• Updated the build pipeline in .goreleaser.yml and mise.toml to inject Version, GitCommit, and BuildDate into the binary using ldflags. [1] [2]
• Changed the default Version string in internal/version/version.go and refactored version variable usage to support the new build metadata.

Backend Support for Version Metadata:

• Modified the backend (handlers.go) to pass version and commit information to templates via a new indexData struct, and imported the version package to support this. [1] [2] [3]