feat: implement basic balance command

app/src/commands/economy/balance.ts

@@ -0,0 +1,13 @@
+import type { Command } from "@lib/types";
+import { getUserBalance } from "@/modules/economy/economy.service";
+import { SlashCommandBuilder, EmbedBuilder } from "discord.js";
+
+export const balance: Command = {
+    data: new SlashCommandBuilder().setName("balance").setDescription("Check your balance"),
+    execute: async (interaction) => {
+        const balance = await getUserBalance(interaction.user.id) || 0;
+        const embed = new EmbedBuilder().setDescription(`Your balance is ${balance}`);
+        await interaction.reply({ embeds: [embed] });
+    }
+};
+