Migrate from Kirby CMS to Hugo with Gokarna theme

- Remove all Kirby/PHP files
- Add Hugo config with Gokarna theme as git submodule
- Add nginx + Hugo Dockerfile replacing PHP/Apache
- Update deploy.php to run hugo after git pull
- Update .gitignore for Hugo output

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "themes/gokarna"]
+	path = themes/gokarna
+	url = https://github.com/gokarna-theme/gokarna-hugo