feat(themes): add popular themes, remove redundant default

- Delete default.css (redundant with dracula.css)
- Add snazzy, catppuccin_mocha, tokyonight, rose_pine, onedark themes
- Update docs/static/style.css to import dracula.css
- Update themes/README.md and syntax-highlighting.md

Theme collection now contains 10 well-designed options.

docs/content/features/syntax-highlighting.md

@@ -192,12 +192,16 @@ sukr uses [lightningcss](https://lightningcss.dev/) which inlines `@import` rule
 
 sukr includes several themes in the `themes/` directory:
 
-- **default.css** — Dracula-inspired dark theme (batteries included)
 - **dracula.css** — Classic Dracula colors
 - **gruvbox.css** — Warm retro palette
 - **nord.css** — Cool arctic colors
 - **github_dark.css** — GitHub's dark mode
 - **github_light.css** — GitHub's light mode
+- **snazzy.css** — Vibrant modern colors
+- **catppuccin_mocha.css** — Warm pastel dark theme
+- **tokyonight.css** — Japanese-inspired dark theme
+- **rose_pine.css** — Elegant soho-inspired theme
+- **onedark.css** — Classic Atom editor theme
 
 Copy the theme files to your project and import as shown above.
 

docs/static/style.css

@@ -1,5 +1,5 @@
 /* sukr docs — clean documentation theme */
-@import "../../themes/default.css";
+@import "../../themes/dracula.css";
 /* Syntax highlighting theme - lightningcss inlines this at build time */
 
 :root {