chore: Build pipeline for books/core

Justfile

@@ -15,5 +15,12 @@ serve:
 deploy: build
     scp -r dist/* {{ user }}@{{ host }}:{{ www-root }}/
 
+core-format:
+    find books/core -type f -name "*.html" -exec npx prettier --write {} \;
+
+core-build:
+    cd books/core && python3 build.py
+    npx prettier --write books/core/index.html
+
 build:
     npm run build