Add devcontainer configuration

devcontainers can be used by IDEs like VSCode to build the whole development environment in a container.
This allows you to keep dependencies, build, and all development aspects separated from any development.
It also allows contributors to instantly have a working, standardized development environment.
It also allows cloud development tools like GitHub Codespaces be automatically setup with the desired environment.

See https://containers.dev/ for more details

.devcontainer/devcontainer.json

@@ -0,0 +1,27 @@
+{
+	"name": "homepage",
+	"build": {
+		"dockerfile": "Dockerfile",
+		"args": {
+			"VARIANT": "18-buster"
+		}
+	},
+	"customizations": {
+		"vscode": {
+			"extensions": [
+				"dbaeumer.vscode-eslint",
+				"mhutchie.git-graph",
+				"streetsidesoftware.code-spell-checker",
+			],
+			"settings": {
+				"eslint.format.enable": true,
+				"eslint.lintTask.enable": true,
+				"eslint.packageManager": "pnpm"
+			}
+		}
+	},
+	"postCreateCommand": ".devcontainer/setup.sh",
+	"forwardPorts": [
+		3000
+	]
+}