refactor: modernize transaction patterns and improve type safety

- Refactored user.service.ts to use withTransaction() helper
- Added 14 comprehensive unit tests for user.service.ts
- Removed duplicate user creation in interactionCreate.ts
- Improved type safety in interaction.routes.ts

src/lib/interaction.routes.ts

@@ -1,10 +1,20 @@
 import { ButtonInteraction, ModalSubmitInteraction, StringSelectMenuInteraction } from "discord.js";
 
-type InteractionHandler = (interaction: any) => Promise<void>;
+// Union type for all component interactions
+type ComponentInteraction = ButtonInteraction | StringSelectMenuInteraction | ModalSubmitInteraction;
 
+// Type for the handler function that modules export
+type InteractionHandler = (interaction: ComponentInteraction) => Promise<void>;
+
+// Type for the dynamically imported module containing the handler
+interface InteractionModule {
+    [key: string]: (...args: any[]) => Promise<void> | any;
+}
+
+// Route definition
 interface InteractionRoute {
-    predicate: (interaction: ButtonInteraction | StringSelectMenuInteraction | ModalSubmitInteraction) => boolean;
-    handler: () => Promise<any>;
+    predicate: (interaction: ComponentInteraction) => boolean;
+    handler: () => Promise<InteractionModule>;
     method: string;
 }