refactor: add inventory view layer

Create inventory.view.ts with UI logic extracted from commands:
- getInventoryEmbed() for inventory display
- getItemUseResultEmbed() for item use results

Updated commands with proper type safety:
- inventory.ts: add null check, convert user.id to string
- use.ts: add null check, convert user.id to string

Improves separation of concerns and type safety.

src/commands/inventory/inventory.ts

@@ -2,7 +2,8 @@ import { createCommand } from "@/lib/utils";
 import { SlashCommandBuilder } from "discord.js";
 import { inventoryService } from "@/modules/inventory/inventory.service";
 import { userService } from "@/modules/user/user.service";
-import { createWarningEmbed, createBaseEmbed } from "@lib/embeds";
+import { createWarningEmbed } from "@lib/embeds";
+import { getInventoryEmbed } from "@/modules/inventory/inventory.view";
 
 export const inventory = createCommand({
     data: new SlashCommandBuilder()
@@ -24,18 +25,19 @@ export const inventory = createCommand({
         }
 
         const user = await userService.getOrCreateUser(targetUser.id, targetUser.username);
-        const items = await inventoryService.getInventory(user.id);
+        if (!user) {
+            await interaction.editReply({ embeds: [createWarningEmbed("Failed to load user data.", "Error")] });
+            return;
+        }
+
+        const items = await inventoryService.getInventory(user.id.toString());
 
         if (!items || items.length === 0) {
             await interaction.editReply({ embeds: [createWarningEmbed("Inventory is empty.", `${user.username}'s Inventory`)] });
             return;
         }
 
-        const description = items.map(entry => {
-            return `**${entry.item.name}** x${entry.quantity}`;
-        }).join("\n");
-
-        const embed = createBaseEmbed(`${user.username}'s Inventory`, description, "Blue");
+        const embed = getInventoryEmbed(items, user.username);
 
         await interaction.editReply({ embeds: [embed] });
     }

src/commands/inventory/use.ts

@@ -2,7 +2,8 @@ import { createCommand } from "@/lib/utils";
 import { SlashCommandBuilder } from "discord.js";
 import { inventoryService } from "@/modules/inventory/inventory.service";
 import { userService } from "@/modules/user/user.service";
-import { createErrorEmbed, createSuccessEmbed } from "@lib/embeds";
+import { createErrorEmbed } from "@lib/embeds";
+import { getItemUseResultEmbed } from "@/modules/inventory/inventory.view";
 import { inventory, items } from "@/db/schema";
 import { eq, and, like } from "drizzle-orm";
 import { DrizzleClient } from "@/lib/DrizzleClient";
@@ -25,9 +26,13 @@ export const use = createCommand({
 
         const itemId = interaction.options.getNumber("item", true);
         const user = await userService.getOrCreateUser(interaction.user.id, interaction.user.username);
+        if (!user) {
+            await interaction.editReply({ embeds: [createErrorEmbed("Failed to load user data.")] });
+            return;
+        }
 
         try {
-            const result = await inventoryService.useItem(user.id, itemId);
+            const result = await inventoryService.useItem(user.id.toString(), itemId);
 
             const usageData = result.usageData;
             if (usageData) {
@@ -53,11 +58,7 @@ export const use = createCommand({
                 }
             }
 
-            const embed = createSuccessEmbed(
-                result.results.map(r => `• ${r}`).join("\n"),
-                `Used ${result.usageData.effects.length > 0 ? 'Item' : 'Item'}` // Generic title, improves below
-            );
-            embed.setTitle("Item Used!");
+            const embed = getItemUseResultEmbed(result.results);
 
             await interaction.editReply({ embeds: [embed] });