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.Host.IntegrationTests/DriverStatusHubE2eTests.cs

@@ -39,6 +39,7 @@ public sealed class DriverStatusHubE2eTests
     ///     to both the <see cref="IDriverStatusSnapshotStore"/> (via <c>Upsert</c>) and the
     ///     mock <see cref="IHubContext{DriverStatusHub}"/> (via <c>SendAsync</c>).
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task StatusHub_BridgeActor_ForwardsHealthChanged_ToStoreAndHub()
     {
@@ -106,6 +107,7 @@ public sealed class DriverStatusHubE2eTests
     ///     for the same instance ID results in the store holding only the most recent state
     ///     (last-write-wins) and both hub push calls being made.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task StatusHub_BridgeActor_LastSnapshotWins_InStore()
     {