Add 18 community AL/BC patterns across style, data-modeling, web-services, appsource, breaking-changes, performance, and testing

Contributed by CURABIS ApS, generalized from patterns observed across real AppSource/PTE development. Each article follows the knowledge file format (frontmatter, Description/Best Practice/Anti Pattern, sibling .good.al/.bad.al samples).

microsoft/knowledge/style/al-identifiers-english.good.al

@@ -0,0 +1,11 @@
+codeunit 50100 "Sales Amount Calculator"
+{
+    procedure CalculateTotalAmount(var SalesLine: Record "Sales Line"): Decimal
+    var
+        TotalAmount: Decimal;
+    begin
+        SalesLine.CalcSums(Amount);
+        TotalAmount := SalesLine.Amount;
+        exit(TotalAmount);
+    end;
+}