Initial project structure for Wrenn Sandbox

Set up directory layout, Makefiles, go.mod files, docker-compose,
and empty placeholder files for all packages.

.gitignore

@@ -0,0 +1,39 @@
+# If you prefer the allow list template instead of the deny list, see community template:
+# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
+#
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Code coverage profiles and other test artifacts
+*.out
+coverage.*
+*.coverprofile
+profile.cov
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+go.work.sum
+
+# env file
+.env
+
+# Editor/IDE
+# .idea/
+.vscode/
+
+## AI
+.claude/
+e2b/
+
+## Builds
+builds/