feat: Implement OAuth2 authentication with Microsoft, Google, and PocketId

- Added JWT configuration to appsettings.json for secure token handling.
- Updated config.json to include OAuth provider details for Microsoft, Google, and PocketId.
- Added Microsoft icon SVG for UI representation.
- Refactored app.config.ts to use a custom AuthInterceptor for managing access tokens.
- Enhanced auth route guard to handle asynchronous authentication checks.
- Created new auth models for structured request and response handling.
- Developed a callback component to manage user login states and transitions.
- Updated side-login component to support multiple OAuth providers with loading states.
- Implemented authentication service methods for handling OAuth login flows and token management.
- Added error handling and user feedback for authentication processes.

Api/Models/DTOs/AuthenticationDtos.cs

@@ -0,0 +1,59 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Api.Models.DTOs
+{
+    public class AuthenticateRequest
+    {
+        [Required]
+        public string IdToken { get; set; } = string.Empty;
+        
+        [Required]
+        public string Provider { get; set; } = string.Empty; // "Microsoft", "Google", "PocketId"
+        
+        /// <summary>
+        /// Optional access token for API calls (e.g., Microsoft Graph)
+        /// </summary>
+        public string? AccessToken { get; set; }
+    }
+    
+    public class AuthenticateResponse
+    {
+        public string AccessToken { get; set; } = string.Empty;
+        public DateTime ExpiresAt { get; set; }
+        public UserProfile User { get; set; } = null!;
+        public bool IsNewUser { get; set; }
+    }
+    
+    public class UserProfile
+    {
+        public int Id { get; set; }
+        public string Email { get; set; } = string.Empty;
+        public string? FirstName { get; set; }
+        public string? LastName { get; set; }
+        public string? ProfilePictureUrl { get; set; }
+        public DateTime CreatedAt { get; set; }
+        public DateTime? LastLoginAt { get; set; }
+        public List<string> Providers { get; set; } = new List<string>();
+    }
+    
+    public class JwtSettings
+    {
+        public string SecretKey { get; set; } = string.Empty;
+        public string Issuer { get; set; } = string.Empty;
+        public string Audience { get; set; } = string.Empty;
+        public int ExpirationMinutes { get; set; } = 60;
+    }
+    
+    public class OAuthProviderSettings
+    {
+        public Dictionary<string, ProviderConfig> Providers { get; set; } = new Dictionary<string, ProviderConfig>();
+    }
+    
+    public class ProviderConfig
+    {
+        public string Authority { get; set; } = string.Empty;
+        public string ClientId { get; set; } = string.Empty;
+        public string? ClientSecret { get; set; }
+        public List<string> ValidAudiences { get; set; } = new List<string>();
+    }
+}