docs: add XML documentation and ConfigManager implementation plans

Add comprehensive XML documentation (param/returns tags) across 132 source
files to improve IntelliSense and API discoverability. Include ConfigManager
design documents and implementation plans for phases 1-9.

NEW/src/JdeScoping.Client/Services/AuthService.cs

@@ -13,6 +13,12 @@ public class AuthService : IAuthService
     private readonly ICryptoService _cryptoService;
     private readonly IAuthStateProvider _authStateProvider;
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AuthService"/> class.
+    /// </summary>
+    /// <param name="httpClient">The HTTP client for API communication.</param>
+    /// <param name="cryptoService">The cryptography service.</param>
+    /// <param name="authStateProvider">The authentication state provider.</param>
     public AuthService(
         HttpClient httpClient,
         ICryptoService cryptoService,
@@ -23,6 +29,11 @@ public class AuthService : IAuthService
         _authStateProvider = authStateProvider;
     }
 
+    /// <summary>
+    /// Authenticates a user with encrypted credentials.
+    /// </summary>
+    /// <param name="model">The login credentials.</param>
+    /// <returns>The login result with user information if successful.</returns>
     public async Task<LoginResultModel> LoginAsync(LoginModel model)
     {
         try
@@ -54,6 +65,9 @@ public class AuthService : IAuthService
         }
     }
 
+    /// <summary>
+    /// Logs out the current user and clears authentication state.
+    /// </summary>
     public async Task LogoutAsync()
     {
         try