Address Jesper Schulz-Wedde's review on PR #158

- use-generateguid-for-unique-test-fixture-values.md: GenerateGUID()
  is a Code[10] number-series value, not a real GUID; truncating it
  with CopyStr for a shorter field cuts off the changing digits. Point
  to GenerateRandomCode/GenerateRandomCodeWithLength/GenerateRandomXMLText
  instead, which verify uniqueness against the actual table.
- Split use-testpage-visible-enabled-to-verify-field-ui-state.md: drop
  its editability claim (the sample opens with OpenView() and asserts
  Enabled(), which verifies enabled state, not editability — Editable()
  and Enabled() are distinct TestField methods). New companion article
  use-testpage-editable-to-verify-field-editability.md covers Editable()
  with OpenEdit() specifically.
- Wire GenerateGUID/CopyStr and TestPage Visible/Enabled/Editable cues
  into al-testing-review.md, and the Item Ledger Entry/Last Shipping No.
  posting cue into al-data-modeling-review.md.

The Item Ledger Entry article itself was independently verified against
current BCApps source and needs no changes.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

microsoft/knowledge/testing/use-testpage-visible-enabled-to-verify-field-ui-state.good.al

@@ -9,7 +9,7 @@ codeunit 50131 "Sample Customer Type UI Test"
         CustomerCard: TestPage "Customer Card";
     begin
         CustomerCard.OpenView();
-        Assert.IsTrue(CustomerCard."Customer Type".Enabled(), 'Customer Type should be editable on the Customer Card.');
+        Assert.IsTrue(CustomerCard."Customer Type".Enabled(), 'Customer Type should be enabled on the Customer Card.');
         Assert.IsTrue(CustomerCard."Customer Type".Visible(), 'Customer Type should be visible on the Customer Card.');
     end;
 }