refactor: split CommandFooter, perf tweaks

- extracted drawer modal to CommandDrawer (~180 lines)
- CommandFooter now under 270 lines
- replaced transition-all with specific props (colors, transform, etc)
- should reduce repaints on hover states

src/lib/scripts/nix.ts

@@ -1,6 +1,4 @@
-/**
- * Nix script generator
- */
+// Nix script - nix-env
 
 import { generateAsciiHeader, generateSharedUtils, escapeShellString, type PackageInfo } from './shared';