feat(ablegacy): B/I/O-file bit-within-word writes via existing RMW path

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriver.cs

@@ -360,12 +360,14 @@ public sealed class AbLegacyDriver : IDriver, IReadable, IWritable, ITagDiscover
             {
                 var parsed = AbLegacyAddress.TryParse(def.Address);
 
-                // PCCC bit-within-word writes — task #181 pass 2. RMW against a parallel
-                // parent-word runtime (strip the /N bit suffix). Per-parent-word lock serialises
-                // concurrent bit writers. Applies to N-file bit-in-word (N7:0/3) + B-file bits
-                // (B3:0/0). T/C/R sub-elements don't hit this path because they're not Bit typed.
-                if (def.DataType == AbLegacyDataType.Bit && parsed?.BitIndex is int bit
-                    && parsed.FileLetter is not "B" and not "I" and not "O")
+                // PCCC bit-within-word writes — RMW against a parallel parent-word runtime (strip the /N
+                // bit suffix). The per-parent-word lock serialises concurrent bit writers. Applies to every
+                // bit-addressable PCCC file: N-file (N7:0/3), B-file (B3:0/0), and the I/O image files
+                // (I:0/0, O:1/2); L-file bits RMW a 32-bit parent, the rest a 16-bit word. T/C/R sub-elements
+                // don't reach this path because they're not Bit typed. NOTE: an Input-image (I) write is sent
+                // to the PLC like any other write — the device drives the input image from physical inputs and
+                // may reject it; we surface that real PCCC status rather than pre-rejecting at the driver.
+                if (def.DataType == AbLegacyDataType.Bit && parsed?.BitIndex is int bit)
                 {
                     results[i] = new WriteResult(
                         await WriteBitInWordAsync(device, parsed, bit, w.Value, cancellationToken).ConfigureAwait(false));