feat: Introduce modular inventory item effect handling and centralize Discord interaction routing.

src/modules/inventory/effects/registry.ts

@@ -0,0 +1,18 @@
+import {
+    handleAddXp,
+    handleAddBalance,
+    handleReplyMessage,
+    handleXpBoost,
+    handleTempRole,
+    handleColorRole
+} from "./handlers";
+import type { EffectHandler } from "./types";
+
+export const effectHandlers: Record<string, EffectHandler> = {
+    'ADD_XP': handleAddXp,
+    'ADD_BALANCE': handleAddBalance,
+    'REPLY_MESSAGE': handleReplyMessage,
+    'XP_BOOST': handleXpBoost,
+    'TEMP_ROLE': handleTempRole,
+    'COLOR_ROLE': handleColorRole
+};