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/query-results-bypass-primary-key-cache.good.al

@@ -0,0 +1,12 @@
+codeunit 50100 "Query Bypass PK Cache Good"
+{
+    procedure CustomerName(CustomerNo: Code[20]): Text
+    var
+        Customer: Record Customer;
+    begin
+        // Repeated Get of the same No. is served from the transaction PK cache.
+        Customer.SetLoadFields(Name);
+        if Customer.Get(CustomerNo) then
+            exit(Customer.Name);
+    end;
+}