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.Browser.Tests/GalaxyDriverBrowserTests.cs

@@ -23,6 +23,7 @@ public sealed class GalaxyDriverBrowserTests
 
     /// <summary>An empty Gateway.Endpoint must fail fast with a clear, endpoint-mentioning
     /// message rather than surfacing a downstream gRPC URI parse error.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task OpenAsync_with_empty_endpoint_throws_InvalidOperationException()
     {
@@ -34,6 +35,7 @@ public sealed class GalaxyDriverBrowserTests
 
     /// <summary>An empty MxAccess.ClientName must fail fast — refused so the gateway
     /// side doesn't see anonymous browse sessions during triage.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task OpenAsync_with_empty_clientName_throws_InvalidOperationException()
     {
@@ -45,6 +47,7 @@ public sealed class GalaxyDriverBrowserTests
 
     /// <summary>A JSON literal that deserializes to null must fail fast with a
     /// "deserialized to null" message — never a downstream NRE.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task OpenAsync_with_null_json_throws_InvalidOperationException()
     {