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.Tests/S7DriverCodeReviewFixTests2.cs

@@ -16,6 +16,7 @@ public sealed class S7DriverCodeReviewFixTests2
     // ── Driver.S7-003 — Read/WriteAsync must throw ArgumentNullException, not NRE ─────────
 
     /// <summary>Verifies that ReadAsync throws ArgumentNullException for null references.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task ReadAsync_with_null_fullReferences_throws_ArgumentNullException()
     {
@@ -28,6 +29,7 @@ public sealed class S7DriverCodeReviewFixTests2
     }
 
     /// <summary>Verifies that WriteAsync throws ArgumentNullException for null writes.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task WriteAsync_with_null_writes_throws_ArgumentNullException()
     {
@@ -39,6 +41,7 @@ public sealed class S7DriverCodeReviewFixTests2
     // ── Driver.S7-009 — Poll loop must update health on sustained failure ────────────────
 
     /// <summary>Verifies that the poll loop degrades health when the driver is uninitialized.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task PollLoop_against_uninitialized_driver_degrades_health()
     {
@@ -68,6 +71,7 @@ public sealed class S7DriverCodeReviewFixTests2
     }
 
     /// <summary>Verifies that the poll loop applies capped backoff after consecutive failures.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task PollLoop_applies_capped_backoff_after_consecutive_failures()
     {
@@ -140,6 +144,7 @@ public sealed class S7DriverCodeReviewFixTests2
 
     /// <summary>Verifies that Initialize rejects not-yet-implemented data types with NotSupportedException.</summary>
     /// <param name="dt">The S7 data type that is not yet implemented.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Theory]
     [InlineData(S7DataType.Int64)]
     [InlineData(S7DataType.UInt64)]
@@ -173,6 +178,7 @@ public sealed class S7DriverCodeReviewFixTests2
     /// <summary>Verifies that Initialize accepts implemented data types.</summary>
     /// <param name="dt">The S7 data type to test.</param>
     /// <param name="addr">The S7 address string corresponding to the data type.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Theory]
     [InlineData(S7DataType.Bool, "DB1.DBX0.0")]
     [InlineData(S7DataType.Byte, "DB1.DBB0")]