Add unit tests for generateNumberToBeGuessed() and isCorrectGuess() methods

- Verified structure and value bounds of generateNumberToBeGuessed()
- Tested correct and incorrect input behavior of isCorrectGuess()
- Set up JUnit 5 with @BeforeEach for Game instantiation
- Improved test readability with @DisplayName annotations

.idea/misc.xml

@@ -0,0 +1,14 @@
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+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="MavenProjectsManager">
+    <option name="originalFiles">
+      <list>
+        <option value="$PROJECT_DIR$/pom.xml" />
+      </list>
+    </option>
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_23" default="true" project-jdk-name="openjdk-23" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>