feat(docker): add Docker setup, environment examples, and architecture docs

.gitignore

@@ -33,6 +33,7 @@ yarn-error.log*
 
 # env files (can opt-in for committing if needed)
 .env*
+!.env.example
 
 # vercel
 .vercel
@@ -47,6 +48,7 @@ logs/*
 source/*
 .cursor/*
 docs/*
+!docs/ARCHITECTURE.md
 test/*
 bin/*
 open-sse/test/*