Move CI, dev tools, and configs from root-level scattered locations into
a
unified `dev/` directory structure. Update all references across build
scripts, documentation, and editor configurations.

Also consolidate editor config generation into build.rs for automated
synchronization of rust-analyzer settings across VS Code and Zed.

Add line numbers, cursor glow effects, and syntax highlighting to
the example viewer. Improve visual design with grid backgrounds,
pill-shaped navigation buttons, and a "cargo add" quick link.