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/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests/AbServerFixture.cs

@@ -55,9 +55,11 @@ public sealed class AbServerFixture : IAsyncLifetime
         }
     }
 
-    /// <inheritdoc />
+    /// <summary>Initializes the fixture asynchronously (no-op for this fixture).</summary>
+    /// <returns>A completed value task.</returns>
     public ValueTask InitializeAsync() => ValueTask.CompletedTask;
-    /// <inheritdoc />
+    /// <summary>Disposes the fixture asynchronously (no-op for this fixture).</summary>
+    /// <returns>A completed value task.</returns>
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
 
     /// <summary>
@@ -65,6 +67,7 @@ public sealed class AbServerFixture : IAsyncLifetime
     ///     <see cref="AbServerFactAttribute"/> / <see cref="AbServerTheoryAttribute"/>
     ///     to decide whether to skip tests on a fresh clone without a running container.
     /// </summary>
+    /// <returns><see langword="true"/> if the server is reachable; <see langword="false"/> otherwise.</returns>
     public static bool IsServerAvailable() =>
         TcpProbe(ResolveHost(), ResolvePort());