Enable parallel execution of core unit tests and fix isolation issues

- Updated `maven/core-unittests/pom.xml` to set `forkCount` to `1C` and `reuseForks` to `true` for significant performance gains.
- Refactored `UITestBase` to use `@BeforeAll` for `Display` initialization (with `@TestInstance(PER_CLASS)`), drastically reducing setup time per test.
- Implemented a comprehensive `reset()` method in `TestCodenameOneImplementation` (clearing files, sockets, DBs, contacts, and static flags like `deviceDensity`) and invoked it in `@AfterEach`.
- Added logic to `UITestBase.tearDownDisplay` to reset `Toolbar` global state and clear `Display`'s pending serial call queues via reflection, preventing cross-test pollution.
- Fixed `SeriesTransitionTest` to handle non-deterministic timing (using wait loops instead of fixed counts) and prevent NPEs during Form initialization.

Author: google-labs-jules[bot]

maven/core-unittests/src/test/java/com/codename1/charts/transitions/SeriesTransitionTest.java

@@ -118,13 +118,17 @@ private static class RecordingForm extends Form {
 
         @Override
         public void registerAnimated(Animation cmp) {
-            registeredAnimations.add(cmp);
+            if (registeredAnimations != null) {
+                registeredAnimations.add(cmp);
+            }
             super.registerAnimated(cmp);
         }
 
         @Override
         public void deregisterAnimated(Animation cmp) {
-            deregisteredAnimations.add(cmp);
+            if (deregisteredAnimations != null) {
+                deregisteredAnimations.add(cmp);
+            }
             super.deregisterAnimated(cmp);
         }
     }

maven/core-unittests/src/test/java/com/codename1/junit/UITestBase.java

@@ -79,9 +79,30 @@ protected void setUpImplementation() {
     protected void tearDownDisplay() throws Exception {
         DisplayTest.flushEdt();
         resetUIManager();
+        com.codename1.ui.Toolbar.setGlobalToolbar(false);
         if (implementation != null) {
             implementation.reset();
         }
+
+        // Clear pending serial calls on the Display to avoid pollution
+        try {
+            Field pendingField = Display.class.getDeclaredField("pendingSerialCalls");
+            pendingField.setAccessible(true);
+            @SuppressWarnings("unchecked")
+            List<Runnable> pending = (List<Runnable>) pendingField.get(display);
+            if (pending != null) {
+                pending.clear();
+            }
+
+            Field runningField = Display.class.getDeclaredField("runningSerialCallsQueue");
+            runningField.setAccessible(true);
+            @SuppressWarnings("unchecked")
+            Deque<Runnable> running = (Deque<Runnable>) runningField.get(display);
+            if (running != null) {
+                running.clear();
+            }
+        } catch (Exception ignored) {
+        }
     }
 
     @AfterAll

maven/core-unittests/src/test/java/com/codename1/testing/TestCodenameOneImplementation.java

@@ -915,6 +915,16 @@ public void reset() {
         audioCaptureFrames.clear();
         incomingConnections.clear();
         resourceAsStreams.clear();
+        deviceDensity = Display.DENSITY_MEDIUM;
+        displayWidth = 1080;
+        displayHeight = 1920;
+        desktopSize = new Dimension(displayWidth, displayHeight);
+        windowBounds = new Rectangle(0, 0, displayWidth, displayHeight);
+        lastWindowSize = null;
+        nativeTitle = false;
+        softkeyCount = 2;
+        thirdSoftButton = false;
+        mutableImagesFast = true;
     }
 
     public List<Object> getCleanupCalls() {