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/feedback/feedback.interaction.ts

@@ -8,7 +8,7 @@ import { UserError } from "@shared/lib/errors";
 
 export const handleFeedbackInteraction = async (interaction: Interaction) => {
     // Handle select menu for choosing feedback type
-    if (interaction.isStringSelectMenu() && interaction.customId === "feedback_select_type") {
+    if (interaction.isStringSelectMenu() && interaction.customId === FEEDBACK_CUSTOM_IDS.SELECT_TYPE) {
         const feedbackType = interaction.values[0] as FeedbackType;
 
         if (!feedbackType) {