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.FOCAS.IntegrationTests/FocasSimFixture.cs

@@ -74,6 +74,7 @@ public sealed class FocasSimFixture : IAsyncDisposable
     }
 
     /// <summary>Disposes the fixture and releases any held resources.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
 
     // ---- Admin API helpers ----
@@ -85,23 +86,27 @@ public sealed class FocasSimFixture : IAsyncDisposable
     /// </summary>
     /// <param name="profileName">The DLL-stem name or OtOpcUa-style alias of the profile to load.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the JSON response from the admin endpoint.</returns>
     public Task<JsonElement> LoadProfileAsync(string profileName, CancellationToken ct = default) =>
         SendAdminAsync("mock_load_profile", new { profile = profileName }, ct);
 
     /// <summary>Deep-merge <paramref name="state"/> into the mock's current state.</summary>
     /// <param name="state">The state object to deep-merge into the mock's current state.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the JSON response from the admin endpoint.</returns>
     public Task<JsonElement> PatchStateAsync(object state, CancellationToken ct = default) =>
         SendAdminAsync("mock_patch", new { state }, ct);
 
     /// <summary>Reset the mock to the selected profile's default state.</summary>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the JSON response from the admin endpoint.</returns>
     public Task<JsonElement> ResetAsync(CancellationToken ct = default) =>
         SendAdminAsync("mock_reset", new { }, ct);
 
     /// <summary>Install a time-scheduled alarm raise / clear sequence.</summary>
     /// <param name="sequence">The alarm sequence events to schedule.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the JSON response from the admin endpoint.</returns>
     public Task<JsonElement> ScheduleAlarmsAsync(IEnumerable<object> sequence, CancellationToken ct = default) =>
         SendAdminAsync("mock_schedule_alarms", new { sequence }, ct);
 
@@ -110,6 +115,7 @@ public sealed class FocasSimFixture : IAsyncDisposable
     /// <param name="method">The admin method name to invoke.</param>
     /// <param name="params">The parameters object to send with the request.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the JSON response from the admin endpoint.</returns>
     public async Task<JsonElement> SendAdminAsync(string method, object @params, CancellationToken ct = default)
     {
         using var client = new TcpClient();