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.Host/Observability/ObservabilityExtensions.cs

@@ -13,6 +13,8 @@ namespace ZB.MOM.WW.OtOpcUa.Host.Observability;
 /// </summary>
 public static class ObservabilityExtensions
 {
+    /// <summary>Adds OtOpcUa observability (metrics and tracing) to the service collection.</summary>
+    /// <param name="services">The service collection to add observability services to.</param>
     public static IServiceCollection AddOtOpcUaObservability(this IServiceCollection services)
     {
         services.AddOpenTelemetry()
@@ -30,6 +32,7 @@ public static class ObservabilityExtensions
     /// <c>app.UseAuthentication/UseAuthorization</c> if metrics access should require auth;
     /// the default leaves it unauthenticated for local Prometheus scrapes.
     /// </summary>
+    /// <param name="app">The endpoint route builder.</param>
     public static IEndpointRouteBuilder MapOtOpcUaMetrics(this IEndpointRouteBuilder app)
     {
         app.MapPrometheusScrapingEndpoint("/metrics");