Add CI

tools/ci/Dockerfile

@@ -0,0 +1,26 @@
+# Build toolchain of CI (.gitea/workflows/release.yaml, docs/development.md «CI»): JDK 21 (Gradle, the desktop app's
+# toolchain and its jpackage) and the Android SDK the TV app compiles against. dpkg-deb for the .deb comes with the base
+# image. Gradle itself comes through the wrapper and, like every dependency, lands in /gradle — a BuildKit cache mount of
+# release.Dockerfile. Bump the platform together with compileSdk in app/build.gradle.kts.
+FROM eclipse-temurin:21-jdk-noble
+
+ARG CMDLINE_TOOLS=16111833
+ARG SDK_PACKAGES="platforms;android-37.0 build-tools;36.0.0"
+
+ENV ANDROID_HOME=/opt/android-sdk
+ENV PATH=$ANDROID_HOME/cmdline-tools/latest/bin:$PATH
+
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends curl unzip \
+ && rm -rf /var/lib/apt/lists/* \
+ && curl -fsSL -o /tmp/tools.zip https://dl.google.com/android/repository/commandlinetools-linux-${CMDLINE_TOOLS}_latest.zip \
+ && mkdir -p $ANDROID_HOME/cmdline-tools \
+ && unzip -q /tmp/tools.zip -d $ANDROID_HOME/cmdline-tools \
+ && mv $ANDROID_HOME/cmdline-tools/cmdline-tools $ANDROID_HOME/cmdline-tools/latest \
+ && rm /tmp/tools.zip \
+ && (yes | sdkmanager --licenses > /dev/null) \
+ && sdkmanager $SDK_PACKAGES
+
+ENV GRADLE_USER_HOME=/gradle \
+    ANDROID_USER_HOME=/gradle/android \
+    GRADLE_OPTS=-Dorg.gradle.daemon=false