docs: backfill XML documentation across 756 files

Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.

tests/Server/ZB.MOM.WW.OtOpcUa.Security.Tests/AuthEndpointsIntegrationTests.cs

@@ -31,6 +31,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
 
     private static CancellationToken Ct => TestContext.Current.CancellationToken;
 
+    /// <summary>Initializes the test host and server.</summary>
     public async ValueTask InitializeAsync()
     {
         var dbName = $"auth-int-tests-{Guid.NewGuid():N}";
@@ -71,6 +72,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
         _server = _host.GetTestServer();
     }
 
+    /// <summary>Disposes the test host and server.</summary>
     public async ValueTask DisposeAsync()
     {
         await _host.StopAsync(TestContext.Current.CancellationToken);
@@ -79,6 +81,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
 
     private HttpClient NewClient() => _server.CreateClient();
 
+    /// <summary>Tests that login with valid credentials returns 204 and sets cookie.</summary>
     [Fact]
     public async Task Login_with_valid_credentials_returns_204_and_sets_cookie()
     {
@@ -90,6 +93,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
         response.Headers.GetValues("Set-Cookie").ShouldContain(c => c.StartsWith("OtOpcUa.Auth="));
     }
 
+    /// <summary>Tests that login with invalid credentials returns 401.</summary>
     [Fact]
     public async Task Login_with_invalid_credentials_returns_401()
     {
@@ -100,6 +104,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
         response.StatusCode.ShouldBe(HttpStatusCode.Unauthorized);
     }
 
+    /// <summary>Tests that login when LDAP throws returns 503.</summary>
     [Fact]
     public async Task Login_when_ldap_throws_returns_503()
     {
@@ -110,6 +115,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
         response.StatusCode.ShouldBe(HttpStatusCode.ServiceUnavailable);
     }
 
+    /// <summary>Tests that ping anonymous returns 401.</summary>
     [Fact]
     public async Task Ping_anonymous_returns_401()
     {
@@ -119,6 +125,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
         response.StatusCode.ShouldBe(HttpStatusCode.Unauthorized);
     }
 
+    /// <summary>Tests that ping after cookie login returns 200.</summary>
     [Fact]
     public async Task Ping_after_cookie_login_returns_200()
     {
@@ -133,6 +140,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
         response.StatusCode.ShouldBe(HttpStatusCode.OK);
     }
 
+    /// <summary>Tests that token after cookie login returns jwt.</summary>
     [Fact]
     public async Task Token_after_cookie_login_returns_jwt()
     {
@@ -152,6 +160,7 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
         token!.Split('.').Length.ShouldBe(3);
     }
 
+    /// <summary>Tests that logout clears the cookie.</summary>
     [Fact]
     public async Task Logout_clears_the_cookie()
     {
@@ -180,6 +189,11 @@ public sealed class AuthEndpointsIntegrationTests : IAsyncLifetime
 
     private sealed class StubLdapAuthService : ILdapAuthService
     {
+        /// <summary>Authenticates a user asynchronously using the stub service.</summary>
+        /// <param name="username">The username to authenticate.</param>
+        /// <param name="password">The password to verify.</param>
+        /// <param name="ct">The cancellation token.</param>
+        /// <returns>The authentication result.</returns>
         public Task<LdapAuthResult> AuthenticateAsync(string username, string password, CancellationToken ct = default)
         {
             if (username == "ldap-down")