feat: enhance inventory schema to support longer ItemSlug and add GiftBox equipment payload handling

DorkNet.Server/Data/DorkNetDbContext.cs

@@ -338,6 +338,7 @@ public class DorkNetDbContext(DbContextOptions<DorkNetDbContext> options) : DbCo
         modelBuilder.Entity<PlayerInventoryEntity>(e =>
         {
             e.HasKey(p => p.Id);
+            e.Property(p => p.ItemSlug).HasMaxLength(128);
             // One row per (player, item) pair.
             e.HasIndex(p => new { p.PlayerId, p.ItemSlug }).IsUnique();
             e.HasIndex(p => p.PlayerId);

DorkNet.Server/Data/Entities/PlayerInventoryEntity.cs

@@ -23,7 +23,7 @@ public class PlayerInventoryEntity
     /// Stored as a string rather than an int FK because a player can
     /// be granted items that aren't in the live store (admin-gifted,
     /// legacy retired items, etc.).</summary>
-    [MaxLength(64)]
+    [MaxLength(128)]
     public string ItemSlug { get; set; } = string.Empty;
 
     public int Quantity { get; set; } = 1;