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/oncompanyopen-subscribers-must-not-do-io.good.al

@@ -0,0 +1,17 @@
+codeunit 50100 "Login Subscriber IO Good"
+{
+    [EventSubscriber(ObjectType::Codeunit, Codeunit::"System Initialization", OnAfterLogin, '', false, false)]
+    local procedure OnAfterLogin()
+    begin
+        // Defer HTTP and heavy SQL to a job; session open must return immediately.
+        TaskScheduler.CreateTask(Codeunit::"Login Subscriber IO Work", Codeunit::"Login Subscriber IO Work", true, CompanyName(), CurrentDateTime());
+    end;
+}
+
+codeunit 50101 "Login Subscriber IO Work"
+{
+    trigger OnRun()
+    begin
+        // Isolated from session creation: outbound I/O is safe here.
+    end;
+}