Add some VSCode and Github Codespaces configuration files

.devcontainer/Dockerfile

@@ -0,0 +1,26 @@
+FROM docker.io/clojure:temurin-21-tools-deps-bookworm
+
+RUN apt-get update && \
+    apt-get install -y git rlwrap npm
+
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=$USER_UID
+
+# Create the user
+RUN groupadd --gid $USER_GID $USERNAME \
+    && useradd --uid $USER_UID --gid $USER_GID -m $USERNAME --shell /bin/bash \
+    #
+    # [Optional] Add sudo support. Omit if you don't need to install software after connecting.
+    && apt-get update \
+    && apt-get install -y sudo \
+    && echo $USERNAME ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/$USERNAME \
+    && chmod 0440 /etc/sudoers.d/$USERNAME
+
+# ********************************************************
+# * Anything else you want to do like clean up goes here *
+# ********************************************************
+
+# [Optional] Set the default user. Omit if you want to keep the default as root.
+USER $USERNAME
+ENTRYPOINT ["/bin/bash"]

.devcontainer/devcontainer.json

@@ -0,0 +1,31 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/debian
+{
+	"name": "endless-ships",
+	"build": {
+		"dockerfile": "Dockerfile"
+	},
+
+	"features": {},
+
+	// Configure tool-specific properties.
+	"customizations": {
+		"vscode":{
+			"extensions": [
+				"betterthantomorrow.calva"
+			]
+		}
+	}
+	/*
+  // unprivileged podman trick, comment if you want to use Docker. Also amend
+  // uid/gid if these don't match yours
+	,"runArgs": [
+		"--userns=keep-id:uid=1000,gid=1000"
+	],
+	"containerUser": "vscode",
+	"updateRemoteUserUID": true,
+	"containerEnv": {
+		"HOME": "/home/vscode"
+	}
+	*/
+}

.gitignore

@@ -7,3 +7,7 @@ data.edn
 /public/js
 /node_modules
 /.cpcache
+# Calva related
+/.clj-kondo/.cache
+/.lsp/.cache
+/.calva/output-window