knowledge(performance): add community rules for JIT, locks, and false positives

These articles capture BC-specific mechanics agents still invert: partial-record JIT on writes, Reset clearing SetLoadFields, HttpClient inside write transactions, and batched number series, plus negative guidance that stops over-eager Query and IsEmpty "fixes".

Co-authored-by: Cursor <cursoragent@cursor.com>

community/knowledge/performance/avoid-currpage-update-in-onaftergetrecord.good.al

@@ -0,0 +1,26 @@
+page 50100 "CurrPage Update OAGR Good"
+{
+    PageType = List;
+    SourceTable = Customer;
+    ApplicationArea = All;
+
+    layout
+    {
+        area(content)
+        {
+            repeater(Rows)
+            {
+                field("No."; Rec."No.") { }
+                field(Warning; WarningText) { }
+            }
+        }
+    }
+
+    var
+        WarningText: Text[50];
+
+    trigger OnAfterGetRecord()
+    begin
+        WarningText := CopyStr(Rec.Name, 1, MaxStrLen(WarningText));
+    end;
+}