Optimize CI workflows by utilizing a dedicated Docker container (ghcr.io/codenameone/codenameone/ci-container) with pre-installed build dependencies (OpenJFX 8, OpenJDK 11/17/21/25, Android SDK/NDK, Ant, Maven).

- Refactor `pr.yml`, `ant.yml`, and `scripts-android.yml` to execute within the container environment, removing redundant setup steps.
- Introduce `.github/workflows/build-container.yml` to automate container image builds.
- Enhance `scripts/setup-workspace.sh` to respect container-provided `CN1_BINARIES` and skip read-only updates.
- Fix `AndroidGradleBuilder.java` to correctly detect the Android SDK root when using `cmdline-tools` directly and ensure `sdkmanager` executes with the correct Java 17 environment.

Author: google-labs-jules[bot]

maven/codenameone-maven-plugin/src/main/java/com/codename1/builders/AndroidGradleBuilder.java

@@ -520,6 +520,7 @@ public boolean build(File sourceZip, final BuildRequest request) throws BuildExc
                 log("NOTICE: Enabling Java 8 source level for Gradle 8 build because RetroLambda is not supported on Java 17, which is required for gradle 8.");
                 useJava8SourceLevel = true;
             }
+            defaultEnvironment.put("JAVA_HOME", getGradleJavaHome());
         }
         if (newFirebaseMessaging && !useGradle8) {
             throw new BuildException("android.newFirebaseMessaging requires gradle version 8.1 or higher.  Please remove the android.gradleVersion build hint");
@@ -577,10 +578,21 @@ public boolean build(File sourceZip, final BuildRequest request) throws BuildExc
         if (!androidSDKDir.exists()) {
             throw new BuildException("Cannot find Android SDK at "+androidHome+".  Please install Android studio, or set the ANDROID_HOME environment variable to point to your android sdk directory.");
         }
-        if (!androidSDKDir.getName().equalsIgnoreCase("sdk")) {
-            androidSDKDir = new File(androidSDKDir, "Sdk");
-            if (!androidSDKDir.isDirectory()) {
-                androidSDKDir = new File(androidSDKDir.getParentFile(), "sdk");
+        // Check if this looks like an SDK directory
+        if (!new File(androidSDKDir, "cmdline-tools").exists() &&
+                !new File(androidSDKDir, "platform-tools").exists() &&
+                !new File(androidSDKDir, "build-tools").exists() &&
+                !new File(androidSDKDir, "tools").exists()) {
+            if (!androidSDKDir.getName().equalsIgnoreCase("sdk")) {
+                File childSdk = new File(androidSDKDir, "Sdk");
+                if (childSdk.isDirectory()) {
+                    androidSDKDir = childSdk;
+                } else {
+                    File siblingSdk = new File(androidSDKDir.getParentFile(), "sdk");
+                    if (siblingSdk.isDirectory()) {
+                        androidSDKDir = siblingSdk;
+                    }
+                }
             }
         }