Switch Caddy to hardened non-root image

.devcontainer/devcontainer.json

@@ -3,7 +3,7 @@
     "workspaceMount": "source=${localWorkspaceFolder},target=/workspace,type=bind,Z",
     "remoteUser": "dev",
     "mounts": [
-      "source=${localEnv:HOME}/.ssh,target=/root/.ssh,type=bind,readonly"
+      "source=${localEnv:HOME}/.ssh,target=/home/dev/.ssh,type=bind,readonly"
     ],
     "build": {
       "dockerfile": "Dockerfile",