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.

src/Server/ZB.MOM.WW.OtOpcUa.Security/Endpoints/AuthEndpoints.cs

@@ -16,8 +16,12 @@ public static class AuthEndpoints
     /// <summary>JSON body schema for API-side login callers (kept stable for tests).</summary>
     public sealed record LoginRequest(string Username, string Password);
 
+    /// <summary>Response for a token issue request.</summary>
     public sealed record TokenResponse(string Token);
 
+    /// <summary>Maps OtOpcUa authentication endpoints to the application route builder.</summary>
+    /// <param name="app">The endpoint route builder.</param>
+    /// <returns>The endpoint route builder for chaining.</returns>
     public static IEndpointRouteBuilder MapOtOpcUaAuth(this IEndpointRouteBuilder app)
     {
         // The login endpoint serves two callers with different ergonomics: