feat: improve book reviews, restore detailed privacy policy, fix header logo, add theme toggle, integrate boneyard-js

- Book reviews: add line-clamp for longer review text with expand/collapse per review
- Privacy policy: restore full detailed DSGVO-compliant fallback content
- Header (legal pages): change logo from 'dk' to 'dk0' in circle
- Header (main page): add ThemeToggle for dark/light mode switching
- Skeleton loading: integrate boneyard-js for ReadBooks, CurrentlyReading, Projects
- Add boneyard.config.json and bones/registry.ts placeholder

.gitignore

@@ -58,6 +58,9 @@ coverage/
 .idea/
 .vscode/
 
+# boneyard generated bones
+bones/*.bones.json
+
 # OS
 .DS_Store
 Thumbs.db