added insuranceSum calculation missing breed, age factors and yearly premium

src/main/java/com/pfefferminzia/petinsurance/animals/Animal.java

@@ -0,0 +1,10 @@
+package com.pfefferminzia.petinsurance.animals;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public sealed interface Animal permits Dog, Cat, SmallAnimal {
+    
+    LocalDate birthday();
+    BigDecimal getBaseInsuranceSum();
+}