fix: improve styling and functionality for 404 and Repository pages
- 404.html: Move x-data directive to wrap entire content including modal, fixing Easter egg button click functionality. Add border, glow, and bg styling to main container.
- repository/list.html: Add border, glow, rounded, and bg styling to article container for consistency with other pages.
- Both pages now have consistent visual styling with borders, glows, and proper background colors.
