Fix admin route access and backend configuration

- Added /admin redirect to login page in nginx config
- Fixed backend server.js route ordering for proper admin handling
- Updated authentication middleware and routes
- Added user management routes
- Configured PostgreSQL integration
- Updated environment configuration

Models/PortfolioCategory.cs

@@ -0,0 +1,33 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization.Attributes;
+
+namespace SkyArtShop.Models;
+
+public class PortfolioCategory
+{
+	[BsonId]
+	[BsonRepresentation(BsonType.ObjectId)]
+	public string? Id { get; set; }
+
+	[Required]
+	public string Name { get; set; } = string.Empty;
+
+	[Required]
+	public string Slug { get; set; } = string.Empty;
+
+	public string Description { get; set; } = string.Empty;
+
+	public string ThumbnailImage { get; set; } = string.Empty;
+
+	public string FeaturedImage { get; set; } = string.Empty;
+
+	public int DisplayOrder { get; set; }
+
+	public bool IsActive { get; set; } = true;
+
+	public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+	public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+}