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.S7.IntegrationTests/S7_1500/S7_1500Profile.cs

@@ -28,6 +28,7 @@ public static class S7_1500Profile
     /// <summary>Builds the S7 driver options for the S7-1500 integration tests.</summary>
     /// <param name="host">The hostname or IP address of the S7 PLC.</param>
     /// <param name="port">The port number for the S7 PLC connection.</param>
+    /// <returns>A <see cref="S7DriverOptions"/> instance pre-configured with the standard S7-1500 test tags.</returns>
     public static S7DriverOptions BuildOptions(string host, int port) => new()
     {
         Host = host,

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests/S7_1500/S7_1500SmokeTests.cs

@@ -18,6 +18,7 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests.S7_1500;
 public sealed class S7_1500SmokeTests(Snap7ServerFixture sim)
 {
     /// <summary>Verifies that the driver reads a seeded u16 value through real S7comm.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task Driver_reads_seeded_u16_through_real_S7comm()
     {
@@ -36,6 +37,7 @@ public sealed class S7_1500SmokeTests(Snap7ServerFixture sim)
     }
 
     /// <summary>Verifies that the driver reads a typed batch of seeded values.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task Driver_reads_seeded_typed_batch()
     {
@@ -60,6 +62,7 @@ public sealed class S7_1500SmokeTests(Snap7ServerFixture sim)
     }
 
     /// <summary>Verifies that the driver can write and then read back a value on a scratch register.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task Driver_write_then_read_round_trip_on_scratch_word()
     {