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.Runtime.Tests/ServiceCollectionExtensionsTests.cs

@@ -18,6 +18,7 @@ namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests;
 public sealed class ServiceCollectionExtensionsTests
 {
     /// <summary>Verifies that WithOtOpcUaRuntimeActors spawns driver host and DB health probe actors.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task WithOtOpcUaRuntimeActors_spawns_driver_host_and_db_health_probe()
     {
@@ -72,6 +73,7 @@ public sealed class ServiceCollectionExtensionsTests
     private sealed class InMemoryConfigDbFactory(string dbName) : IDbContextFactory<OtOpcUaConfigDbContext>
     {
         /// <summary>Creates a new in-memory database context.</summary>
+        /// <returns>A new <see cref="OtOpcUaConfigDbContext"/> instance backed by an in-memory database.</returns>
         public OtOpcUaConfigDbContext CreateDbContext()
         {
             var opts = new DbContextOptionsBuilder<OtOpcUaConfigDbContext>()
@@ -84,22 +86,19 @@ public sealed class ServiceCollectionExtensionsTests
     /// <summary>Fake cluster role information for testing.</summary>
     private sealed class FakeClusterRoleInfo : IClusterRoleInfo
     {
-        /// <summary>Gets the local node ID.</summary>
+        /// <inheritdoc />
         public NodeId LocalNode { get; } = NodeId.Parse("test-node");
-        /// <summary>Gets the local roles.</summary>
+        /// <inheritdoc />
         public IReadOnlySet<string> LocalRoles { get; } = new HashSet<string>(["driver"]);
-        /// <summary>Determines whether the local node has the specified role.</summary>
-        /// <param name="role">The role to check.</param>
+        /// <inheritdoc />
         public bool HasRole(string role) => LocalRoles.Contains(role);
 
-        /// <summary>Gets the members with the specified role.</summary>
-        /// <param name="role">The role to query.</param>
+        /// <inheritdoc />
         public IReadOnlyList<NodeId> MembersWithRole(string role) => Array.Empty<NodeId>();
 
-        /// <summary>Gets the leader node for the specified role.</summary>
-        /// <param name="role">The role to query.</param>
+        /// <inheritdoc />
         public NodeId? RoleLeader(string role) => null;
-        /// <summary>Raised when the role leader changes.</summary>
+        /// <inheritdoc />
         public event EventHandler<RoleLeaderChangedEventArgs>? RoleLeaderChanged
         {
             add { _ = value; }