fix(driver-ablegacy): resolve Medium code-review finding (Driver.AbLegacy-002)

`current & widthMask` was already applied in `WriteBitInWordAsync` by
the -001 High finding fix, making the 16-bit sign-extension hazard fully
neutralised. No further code change required; mark Resolved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

code-reviews/Driver.AbLegacy/findings.md

@@ -66,7 +66,7 @@ RMW arithmetic to the native width so sign-extension can no longer corrupt high
 | Severity | Medium |
 | Category | Correctness & logic bugs |
 | Location | `AbLegacyDriver.cs:368` |
-| Status | Open |
+| Status | Resolved |
 
 **Description:** In `WriteBitInWordAsync` the parent word is decoded with
 `Convert.ToInt32(parentRuntime.DecodeValue(AbLegacyDataType.Int, ...))`.
@@ -82,7 +82,7 @@ will break silently. Combined with finding 001 this is a latent correctness haza
 operate on an explicitly 16-bit value, or document the reliance on low-16-bit
 preservation explicitly.
 
-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-22 — `current & widthMask` already applied in `WriteBitInWordAsync` by the -001 fix; no additional change needed.
 
 ### Driver.AbLegacy-003
 
@@ -91,7 +91,7 @@ preservation explicitly.
 | Severity | Medium |
 | Category | Correctness & logic bugs |
 | Location | `AbLegacyAddress.cs:62-95` |
-| Status | Open |
+| Status | Resolved |
 
 **Description:** `TryParse` does not reject several malformed PCCC addresses that the
 XML docs imply are invalid:
@@ -108,7 +108,7 @@ through to libplctag rather than rejected early with a clear error.
 reject file numbers on I/O/S, and restrict which file letters may carry a sub-element
 (T/C/R only). Add unit coverage for the rejection cases.
 
-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-22 — `TryParse` now rejects sub-element+bit-index combinations, file numbers on I/O/S files, and sub-elements on non-T/C/R files; unit tests added in `AbLegacyAddressTests`.
 
 ### Driver.AbLegacy-004