CI: export JAVA_HOME and persist sdk.dir for build step

.forgejo/workflows/build_release.yml

@@ -65,6 +65,11 @@ jobs:
             fi
             java -version
           fi
+          if command -v javac >/dev/null 2>&1; then
+            javac -version
+            java_home="$(dirname "$(dirname "$(readlink -f "$(command -v javac)")")")"
+            echo "JAVA_HOME=$java_home" >> "$GITHUB_ENV"
+          fi
 
       - name: Prepare release metadata
         id: prepare
@@ -151,6 +156,9 @@ jobs:
 
       - name: Build app
         run: |
+          if [ -n "${ANDROID_HOME:-}" ]; then
+            printf 'sdk.dir=%s\n' "$ANDROID_HOME" > local.properties
+          fi
           export GRADLE_USER_HOME="${PWD}/.gradle-ci"
           ./gradlew --no-daemon --max-workers=1 \
             "-Dorg.gradle.jvmargs=-Xmx1152m -XX:MaxMetaspaceSize=512m -XX:ReservedCodeCacheSize=128m -Dfile.encoding=UTF-8" \