docs: complete XML doc comments via fixdocs (2757 to 131 findings)

Add missing <returns>/<param>/<summary>/<typeparam> tags and clean up
misused inheritdoc across 481 files so the documented API surface is
complete. Documentation-only (zero code lines changed). The 131 remaining
findings are inheritdoc-style warnings deliberately left to preserve
hand-written implementation rationale (plan-decision notes, race-condition
explanations).

tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DockerFixtureAvailability.cs

@@ -17,6 +17,7 @@ public static class DockerFixtureAvailability
     /// <param name="host">The host to probe.</param>
     /// <param name="port">The TCP port to connect to.</param>
     /// <param name="timeoutMs">Maximum time to wait in milliseconds; defaults to 500.</param>
+    /// <returns><see langword="true"/> if the TCP connection succeeded within the timeout; otherwise <see langword="false"/>.</returns>
     public static bool IsReachable(string host, int port, int timeoutMs = 500)
     {
         try
@@ -43,6 +44,7 @@ public static class DockerFixtureAvailability
     /// </summary>
     /// <param name="endpoint">Endpoint in <c>host:port</c> format.</param>
     /// <param name="timeoutMs">Maximum time to wait in milliseconds; defaults to 500.</param>
+    /// <returns><see langword="true"/> if the TCP connection succeeded within the timeout; otherwise <see langword="false"/>.</returns>
     public static bool IsReachable(string endpoint, int timeoutMs = 500)
     {
         try