Fix remaining JUnit Jupiter compilation errors: missing imports and assertNotEquals argument order

- ChatResponseTest: add missing assertNull static import
- LlamaPublisherTest: add missing fail static import
- LoadProgressCallbackTest: swap assertNotEquals args to message-last order

https://claude.ai/code/session_01Wz6qiYa6SGNirh9tVs4jUL

Author: claude

src/test/java/net/ladenthin/llama/ChatResponseTest.java

@@ -9,6 +9,7 @@
 
 import java.util.List;
 
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 

src/test/java/net/ladenthin/llama/LlamaPublisherTest.java

@@ -14,6 +14,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 
+import static org.junit.jupiter.api.Assertions.fail;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;

src/test/java/net/ladenthin/llama/LoadProgressCallbackTest.java

@@ -52,7 +52,7 @@ public void receivesProgressUpdates() {
             assertTrue(updates.get(i) >= updates.get(i - 1), "progress decreased at index " + i + ": " + updates.get(i - 1) + " -> " + updates.get(i));
         }
         // Sanity: progress actually advanced
-        assertNotEquals("progress never advanced", updates.get(0), updates.get(updates.size() - 1));
+        assertNotEquals(updates.get(0), updates.get(updates.size() - 1), "progress never advanced");
     }
 
     @Test