chore(docker): compose, entrypoint guard, LF shell script; format with Prettier

- Add docker-compose.yml (build context .) and .gitattributes for entrypoint LF
- README: document docker compose and gregWiki root requirement
- package.json: include docker-compose.yml in npm run format

Made-with: Cursor

README.md

@@ -24,9 +24,11 @@ Optional: refresh the legacy GitHub Wiki mirror from a sibling `../.wiki/` clone
 
 ## Docker
 
-Build context is this repository root:
+Build context **must** be this repository root (the folder that contains `package.json`):
 
 ```bash
+docker compose up --build
+# or
 docker build -t gregwiki-docs .
 docker run --rm -p 3000:3000 gregwiki-docs
 ```