tooling: Add devcontainer for Python/MicroPython development.

Author: nedseb

.devcontainer/Dockerfile

@@ -0,0 +1,22 @@
+FROM mcr.microsoft.com/devcontainers/python:3.10
+
+# System packages for firmware build and board communication
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc-arm-none-eabi \
+    libnewlib-arm-none-eabi \
+    openocd \
+    && rm -rf /var/lib/apt/lists/*
+
+# Node.js 20 (for husky, commitlint, lint-staged, semantic-release)
+ARG NODE_VERSION=20
+RUN curl -fsSL https://deb.nodesource.com/setup_${NODE_VERSION}.x | bash - \
+    && apt-get install -y --no-install-recommends nodejs \
+    && rm -rf /var/lib/apt/lists/*
+
+# GitHub CLI
+RUN curl -fsSL https://cli.github.com/packages/githubcli-archive-keyring.gpg \
+    | dd of=/usr/share/keyrings/githubcli-archive-keyring.gpg \
+    && echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/githubcli-archive-keyring.gpg] https://cli.github.com/packages stable main" \
+    > /etc/apt/sources.list.d/github-cli.list \
+    && apt-get update && apt-get install -y --no-install-recommends gh \
+    && rm -rf /var/lib/apt/lists/*

.devcontainer/devcontainer.json

@@ -0,0 +1,24 @@
+{
+  "name": "STeaMi MicroPython Dev",
+  "build": {
+    "dockerfile": "Dockerfile"
+  },
+  "postCreateCommand": "make setup",
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "charliermarsh.ruff",
+        "ms-python.python"
+      ],
+      "settings": {
+        "python.defaultInterpreterPath": "/usr/local/bin/python",
+        "python.testing.pytestEnabled": true,
+        "python.testing.pytestArgs": ["-v", "-k", "mock"],
+        "editor.formatOnSave": true,
+        "[python]": {
+          "editor.defaultFormatter": "charliermarsh.ruff"
+        }
+      }
+    }
+  }
+}

CONTRIBUTING.md

@@ -83,6 +83,16 @@ docs: Update README driver table.
 test(mcp23009e): Add mock scenarios for mcp23009e driver.
 ```
 
+## Dev Container
+
+A dev container is available for VS Code and GitHub Codespaces. It provides Python 3.10, Node.js 20, ruff, pytest, mpremote, arm-none-eabi-gcc, OpenOCD, and the GitHub CLI — everything needed to lint, test, and build firmware.
+
+1. Open the repository in VS Code
+2. When prompted, click **Reopen in Container** (or use the command palette: *Dev Containers: Reopen in Container*)
+3. The container runs `make setup` automatically on creation
+
+All `make` targets work inside the container. Hardware tests and firmware flashing require USB passthrough to the STeaMi board.
+
 ## Workflow
 
 1. Set up your environment: `make setup`