Rename Screenshots/* → ASSETS/Screenshots/* and update README image URLs. Major cleanup and rewrite of theme.css: add :root tokens, consolidate neon color variables, restructure image, code-block, table and callout styles, improve syntax token colors, hover effects, and reduced-motion support. Also remove duplicated README header and tweak content organization. Primarily a styling/documentation refactor to centralize assets and modernize the theme.
Add manifest.json with package metadata; add new assets (logo, callouts gif, screenshots) and remove icon.gif. Update README header to use the beakers asset and rename a screenshot. Expand theme.css with multiple neon-themed UI tweaks: header icon, folder icon, animations, keyframes, and a set of illustrated callout styles and variants referencing the new assets.
