fix(driver-ablegacy): resolve Medium code-review finding (Driver.AbLegacy-012)

Consume previously-dead AbLegacyPlcFamilyProfile fields:

- DeviceState.EffectiveCipPath applies DefaultCipPath when the parsed host
  address has an empty CIP path (SLC 500 / PLC-5 misconfigured without /1,0
  now gets the profile-supplied default route). All three tag/parent/probe
  Create() callers updated.
- InitializeAsync validates each tag's DataType against SupportsLongFile /
  SupportsStringFile and throws InvalidOperationException at init time so a
  MicroLogix Long tag or similar fails early rather than at runtime with an
  opaque comms error.
- MaxTagBytes tracked as a follow-up (string/array chunking requires broader
  design work).

Tests added for CipPath fallback and Long/String type validation.

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

code-reviews/Driver.AbLegacy/findings.md

@@ -315,7 +315,7 @@ rather than blocking on the async path.
 | Severity | Medium |
 | Category | Design-document adherence |
 | Location | `PlcFamilies/AbLegacyPlcFamilyProfile.cs:7-54`, `AbLegacyDriver.cs:48-52` |
-| Status | Open |
+| Status | Resolved |
 
 **Description:** `AbLegacyPlcFamilyProfile` declares four record properties -
 `DefaultCipPath`, `MaxTagBytes`, `SupportsStringFile`, `SupportsLongFile` - and only
@@ -336,7 +336,7 @@ the host CIP path is empty; reject `Long`/`String` tags against families whose p
 sets the corresponding flag false; use `MaxTagBytes` for validation) or remove the
 unused fields and the doc comments that imply they are load-bearing.
 
-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-22 — `DeviceState.EffectiveCipPath` applies `DefaultCipPath` when the parsed host address has an empty CIP path; `InitializeAsync` validates `Long`/`String` tag types against `SupportsLongFile`/`SupportsStringFile` and throws early; `MaxTagBytes` tracked as a follow-up (string/array chunking requires broader design work).
 
 ### Driver.AbLegacy-013