test: add core unit tests

- Add JUnit 5 Jupiter dependencies to pom.xml
- Add maven-surefire-plugin for test execution
- Add AbstractShapeTest for base class methods
- Add SCircleTest, SRectangleTest, STriangleTest, STextTest

Tests cover: creation, bounds, clone, resize (AbstractShape)

src/test/java/ovh/gasser/newshapes/shapes/STriangleTest.java

@@ -0,0 +1,37 @@
+package ovh.gasser.newshapes.shapes;
+
+import org.junit.jupiter.api.Test;
+import java.awt.Color;
+import java.awt.Rectangle;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class STriangleTest {
+    @Test
+    void testCreate() {
+        STriangle triangle = STriangle.create(10, 20, 50, Color.RED, Color.BLACK);
+        assertNotNull(triangle);
+        assertEquals(50, triangle.getBounds().width);
+        assertEquals(50, triangle.getBounds().height);
+    }
+
+    @Test
+    void testCloneCreatesIndependentCopy() {
+        STriangle original = STriangle.create(0, 0, 30, Color.BLUE, Color.BLACK);
+        Object cloneObj = original.clone();
+        assertNotSame(original, cloneObj);
+        assertTrue(cloneObj instanceof STriangle);
+        STriangle clone = (STriangle) cloneObj;
+        assertEquals(original.getBounds(), clone.getBounds());
+    }
+
+    @Test
+    void testBoundsAreSetCorrectly() {
+        STriangle triangle = STriangle.create(5, 10, 25, Color.GREEN, Color.BLACK);
+        Rectangle bounds = triangle.getBounds();
+        assertEquals(5, bounds.x);
+        assertEquals(10, bounds.y);
+        assertEquals(25, bounds.width);
+        assertEquals(25, bounds.height);
+    }
+}