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/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Browsing/BrowseSessionReaperTests.cs

@@ -14,6 +14,8 @@ public sealed class BrowseSessionReaperTests
     private static BrowseSessionReaper NewReaper(BrowseSessionRegistry registry) =>
         new(registry, NullLogger<BrowseSessionReaper>.Instance);
 
+    /// <summary>Verifies that ReapOnceAsync evicts a session that has been idle beyond the timeout.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task ReapOnceAsync_evicts_idle_session()
     {
@@ -31,6 +33,8 @@ public sealed class BrowseSessionReaperTests
         session.Disposed.ShouldBeTrue();
     }
 
+    /// <summary>Verifies that ReapOnceAsync preserves a recently used session.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task ReapOnceAsync_preserves_recent_session()
     {
@@ -45,6 +49,8 @@ public sealed class BrowseSessionReaperTests
         session.Disposed.ShouldBeFalse();
     }
 
+    /// <summary>Verifies that ReapOnceAsync handles a session already removed from the registry without throwing.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task ReapOnceAsync_handles_already_removed_session()
     {
@@ -65,6 +71,8 @@ public sealed class BrowseSessionReaperTests
         session.Disposed.ShouldBeFalse();
     }
 
+    /// <summary>Verifies that ReapOnceAsync continues processing remaining sessions when one session's dispose throws.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task ReapOnceAsync_continues_when_one_session_dispose_throws()
     {