knowledge(performance): align SetLoadFields placement with AL Guidelines (#120)

The AL Guidelines mark `SetLoadFields` placed before `SetRange`/`SetFilter`
as bad code and recommend filters first, while the BCQuality samples used
the opposite order — contradictory guidance across two Microsoft repos.

Per Learn (`Record.SetLoadFields`), "fields that are filtered upon are
always loaded", so the two orders produce an identical projection. The
upstream rule is a readability convention: keep `SetLoadFields` adjacent
to the read it governs.

- Reorder filters ahead of `SetLoadFields` in the six affected AL samples.
- State the placement convention in the Best Practice section.
- Record in Description that order does not change the projection, and
  that only a fieldless `SetLoadFields()` or a later overwriting call does.
- Add an Anti Pattern note so review agents treat the reverse order as a
  readability observation, never a performance defect.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

microsoft/knowledge/performance/load-only-primary-key-fields-for-reference-work.good.al

@@ -6,8 +6,8 @@ codeunit 50100 "Item Reindex Queue"
         ReindexQueue: Codeunit "Reindex Queue";
     begin
         // Only the primary key is used in the loop body; load nothing else.
-        Item.SetLoadFields("No.");
         Item.SetRange("Item Category Code", CategoryCode);
+        Item.SetLoadFields("No.");
 
         if Item.FindSet() then
             repeat