feat: standardize command error handling (Sprint 4)

- Create withCommandErrorHandling utility in bot/lib/commandUtils.ts
- Migrate economy commands: daily, exam, pay, trivia
- Migrate inventory command: use
- Migrate admin/moderation commands: warn, case, cases, clearwarning,
  warnings, note, notes, create_color, listing, webhook, refresh,
  terminal, featureflags, settings, prune
- Add 9 unit tests for the utility
- Update AGENTS.md with new recommended error handling pattern

bot/commands/economy/pay.ts

@@ -5,7 +5,7 @@ import { economyService } from "@shared/modules/economy/economy.service";
 import { userService } from "@shared/modules/user/user.service";
 import { config } from "@shared/lib/config";
 import { createErrorEmbed, createSuccessEmbed } from "@lib/embeds";
-import { UserError } from "@shared/lib/errors";
+import { withCommandErrorHandling } from "@lib/commandUtils";
 
 export const pay = createCommand({
     data: new SlashCommandBuilder()
@@ -50,20 +50,14 @@ export const pay = createCommand({
             return;
         }
 
-        try {
-            await interaction.deferReply();
-            await economyService.transfer(senderId, receiverId.toString(), amount);
+        await withCommandErrorHandling(
+            interaction,
+            async () => {
+                await economyService.transfer(senderId, receiverId.toString(), amount);
 
-            const embed = createSuccessEmbed(`Successfully sent ** ${amount}** Astral Units to <@${targetUser.id}>.`, "💸 Transfer Successful");
-            await interaction.editReply({ embeds: [embed], content: `<@${receiverId}>` });
-
-        } catch (error: any) {
-            if (error instanceof UserError) {
-                await interaction.editReply({ embeds: [createErrorEmbed(error.message)] });
-            } else {
-                console.error("Error sending payment:", error);
-                await interaction.editReply({ embeds: [createErrorEmbed("An unexpected error occurred.")] });
+                const embed = createSuccessEmbed(`Successfully sent ** ${amount}** Astral Units to <@${targetUser.id}>.`, "💸 Transfer Successful");
+                await interaction.editReply({ embeds: [embed], content: `<@${receiverId}>` });
             }
-        }
+        );
     }
 });