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.Galaxy.Tests/GalaxyDriverFactoryTests.cs

@@ -125,6 +125,7 @@ public sealed class GalaxyDriverFactoryTests
     }
 
     /// <summary>Verifies that driver lifecycle toggles health state on initialize and shutdown.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task DriverLifecycle_InitializeShutdown_ToggleHealth()
     {
@@ -148,6 +149,7 @@ public sealed class GalaxyDriverFactoryTests
     }
 
     /// <summary>Verifies that reinitializing with equivalent config refreshes health.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task ReinitializeAsync_RefreshesHealth_WhenConfigIsEquivalent()
     {
@@ -218,6 +220,7 @@ public sealed class GalaxyDriverFactoryTests
     }
 
     /// <summary>Verifies that initializing after dispose throws an exception.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task InitializeAfterDispose_Throws()
     {
@@ -244,6 +247,7 @@ public sealed class GalaxyDriverFactoryTests
     }
 
     /// <summary>Verifies that GetHostStatuses returns an empty snapshot after initialization with seam.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task GetHostStatuses_AfterInitWithSeam_ReturnsEmptySnapshot()
     {