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/DriverReconnectE2eTests.cs

@@ -37,6 +37,7 @@ public sealed class DriverReconnectE2eTests
     ///     to a deployed driver, so no <c>DriverInstanceActor</c> will act on the DPS
     ///     broadcast — the test is validating the command ingestion and reply path only.</para>
     /// </summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task Reconnect_RoundTrip_ReturnsOk()
     {
@@ -63,6 +64,7 @@ public sealed class DriverReconnectE2eTests
     ///     is also accepted (idempotent at the actor layer — the actor simply re-broadcasts
     ///     to DPS and writes another <c>ConfigEdit</c> row).
     /// </summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task Reconnect_IsIdempotent_SecondCallAlsoReturnsOk()
     {