refactor: centralize custom interaction IDs into constants

Replace all hardcoded custom ID strings with module-level constants.
Each module now has *_CUSTOM_IDS in its types file, using functions
for dynamic IDs and PREFIX for startsWith matching.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bot/modules/inventory/inventory.interaction.ts

@@ -3,6 +3,7 @@ import { inventoryService } from "@shared/modules/inventory/inventory.service";
 import { getLootboxResultMessage } from "./inventory.view";
 import type { ItemUsageData } from "@shared/lib/types";
 import { getGuildConfig } from "@shared/lib/config";
+import { INVENTORY_CUSTOM_IDS } from "./inventory.types";
 
 export interface InventoryState {
     ownerId: string;
@@ -25,7 +26,7 @@ export function parseInventoryCustomId(customId: string): { action: string; view
  * Checks if a custom ID belongs to the inventory system.
  */
 export function isInventoryInteraction(customId: string): boolean {
-    return customId.startsWith("inv_");
+    return customId.startsWith(INVENTORY_CUSTOM_IDS.PREFIX);
 }
 
 /**