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/Core/ZB.MOM.WW.OtOpcUa.Configuration.Tests/ResilientConfigReaderTests.cs

@@ -26,6 +26,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     }
 
     /// <summary>Verifies that successful central DB reads return value and mark fresh.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task CentralDbSucceeds_ReturnsValue_MarksFresh()
     {
@@ -45,6 +46,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     }
 
     /// <summary>Verifies that exhausted retries fall back to cache and mark stale.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task CentralDbFails_ExhaustsRetries_FallsBackToCache_MarksStale()
     {
@@ -78,6 +80,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     }
 
     /// <summary>Verifies that DB failure with unavailable cache throws.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task CentralDbFails_AndCacheAlsoUnavailable_Throws()
     {
@@ -99,6 +102,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     }
 
     /// <summary>Verifies that cancellation is not retried.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task Cancellation_NotRetried()
     {
@@ -133,6 +137,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     // ------------------------------------------------------------------------------------
 
     /// <summary>Verifies that command timeout TaskCanceledException falls back to cache.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task CommandTimeout_TaskCanceledException_FallsBackToCache()
     {
@@ -163,6 +168,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     }
 
     /// <summary>Verifies that Polly timeout rejection falls back to cache.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task PollyTimeout_TimeoutRejectedException_FallsBackToCache()
     {
@@ -201,6 +207,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     // ------------------------------------------------------------------------------------
 
     /// <summary>Verifies that fallback warnings do not log exceptions or password fragments.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task FallbackWarning_does_not_log_full_exception_object_or_password_fragment()
     {
@@ -242,6 +249,7 @@ public sealed class ResilientConfigReaderTests : IDisposable
     }
 
     /// <summary>Verifies that caller cancellation propagates rather than falling back.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task CallerCancellation_Propagates_NotFallback()
     {