Add Dockerfile and build workflow

.github/workflows/docker-image.yml

@@ -0,0 +1,32 @@
+name: Build Docker
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repo
+      uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: |
+        docker build \
+          . \
+          --file Dockerfile \
+          --tag amulet-editor:latest \
+          --build-arg AMULET_VERSION=CUSTOM:git+https://github.com/Amulet-Team/Amulet-Map-Editor.git@${{ github.event.release.tag_name }}
+
+    - name: Save Docker image to tar archive
+      run: |
+        docker save amulet-editor:latest -o amulet-editor.tar
+
+    - name: Upload Release Asset
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      run: |
+        gh release upload ${{ github.event.release.tag_name }} \
+          amulet-editor.tar#Amulet-v${{ github.event.release.tag_name }}-docker.tar

Dockerfile

@@ -0,0 +1,19 @@
+FROM python:3.9-bullseye
+RUN apt-get update && apt install libgtk-3-dev dbus-x11 wget libnotify4 -y
+RUN pip install --upgrade pip
+RUN wget https://extras.wxpython.org/wxPython4/extras/linux/gtk3/debian-11/wxPython-4.2.0-cp39-cp39-linux_x86_64.whl && pip install wxPython-4.2.0-cp39-cp39-linux_x86_64.whl
+ARG AMULET_VERSION=RELEASE  # defaults to the latest version if no arg is given in build command.
+RUN if [ "$(echo "$AMULET_VERSION" | cut -c1-7)" = "CUSTOM:" ]; then \
+        pip install "$(echo "$AMULET_VERSION" | cut -c8-)"; \
+    elif [ "$AMULET_VERSION" = "RELEASE" ]; then \
+        pip install --upgrade --upgrade-strategy eager amulet-map-editor; \
+    elif [ "$AMULET_VERSION" = "BETA" ]; then \
+        pip install --upgrade --upgrade-strategy eager amulet-map-editor>=0b0; \
+    elif [ "$AMULET_VERSION" = "ALPHA" ]; then \
+        pip install --upgrade --upgrade-strategy eager amulet-map-editor>=0a0; \
+    else \
+        pip install --upgrade --upgrade-strategy eager amulet-map-editor==$AMULET_VERSION; \
+    fi
+RUN apt-get install libSDL2-2.0 -y
+
+ENTRYPOINT [ "/usr/local/bin/python", "-m", "amulet_map_editor" ]