feat(model): track visited rooms on Player for the map

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Semesterprojekt/src/test/java/thb/jeanluc/adventure/model/PlayerTest.java

@@ -54,4 +54,20 @@ class PlayerTest {
 
         assertThat(p.getCurrentRoom()).isEqualTo(b);
     }
+
+    @Test
+    void startRoomIsVisitedFromTheStart() {
+        Room start = new Room("kitchen", "Kitchen", "desc");
+        Player p = new Player(start, 0);
+        assertThat(p.getVisitedRoomIds()).containsExactly("kitchen");
+    }
+
+    @Test
+    void movingMarksTheNewRoomVisited() {
+        Room start = new Room("kitchen", "Kitchen", "desc");
+        Room hall = new Room("hallway", "Hallway", "desc");
+        Player p = new Player(start, 0);
+        p.setCurrentRoom(hall);
+        assertThat(p.getVisitedRoomIds()).containsExactly("kitchen", "hallway");
+    }
 }