runelite-client: Centralize the high alchemy multiplier

runelite-api/src/main/java/net/runelite/api/Constants.java

@@ -108,4 +108,10 @@ public class Constants
 	 */
 	public static final int ITEM_SPRITE_HEIGHT = 32;
 
+	/**
+	 * High alchemy = shop price * HIGH_ALCHEMY_MULTIPLIER
+	 *
+	 * @see ItemComposition#getPrice
+	 */
+	public static final float HIGH_ALCHEMY_MULTIPLIER = .6f;
 }

runelite-api/src/main/java/net/runelite/api/ItemComposition.java

@@ -87,6 +87,8 @@ public interface ItemComposition
 	 * alchemy values, respectively.
 	 *
 	 * @return the general store value of the item
+	 *
+	 * @see Constants#HIGH_ALCHEMY_MULTIPLIER
 	 */
 	int getPrice();