Add doc to script file

src/constants/defaults.ts

@@ -1,4 +1,13 @@
-// Application constants
+/**
+ * Application Constants and Type Definitions
+ *
+ * Defines TypeScript interfaces for application state, pharmacokinetic parameters,
+ * and default values. Central configuration for localStorage keys and conversion factors.
+ *
+ * @author Andreas Weyer
+ * @license MIT
+ */
+
 export const LOCAL_STORAGE_KEY = 'medPlanAssistantState_v5';
 export const LDX_TO_DAMPH_CONVERSION_FACTOR = 0.2948;