add readme

http-api/uv.lock

@@ -522,7 +522,7 @@ wheels = [
 
 [[package]]
 name = "layercake"
-version = "0.3.0"
+version = "0.3.3"
 source = { directory = "../layercake" }
 dependencies = [
     { name = "arnparse" },
@@ -568,7 +568,6 @@ dev = [
     { name = "jsonlines", specifier = ">=4.0.0" },
     { name = "pytest", specifier = ">=8.3.5" },
     { name = "pytest-cov", specifier = ">=6.0.0" },
-    { name = "pytest-env", specifier = ">=1.1.5" },
     { name = "ruff", specifier = ">=0.11.1" },
 ]