Add new action skills for AL testing and documentation

- Introduced `al-test-writer` to generate AL test codeunits for production objects based on TDD principles.
- Added `al-userguide-test-writer` to create test codeunits from user guide steps, mapping actions and assertions.
- Implemented `bc-extension-test-guide` to generate a comprehensive TEST_GUIDE.md for Business Central extensions, covering various categories.
- Created `bc-webclient-runner` to automate UI testing of the Business Central web client, capturing screenshots and asserting UI states.
- Developed `page-scripting-e2e` to produce a recording plan for Page Scripting, ensuring a structured approach to browser-level testing.

custom/knowledge/integration/never-call-external-services-from-posting.good.al

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+// Best practice: the posting subscriber only STAGES an outbound message and returns.
+// The HttpClient.Send happens later, in a Job Queue codeunit, outside the posting lock.
+// The row is inserted inside the posting transaction, so it exists only if the post
+// committed; the callout runs in a separate transaction where a remote outage can only
+// delay delivery, never roll back a posted shipment.
+
+codeunit 50110 "Post Shipment Notifier"
+{
+    // Subscriber on the real posting publisher. It runs while posting locks are held,
+    // so it must do nothing that can block: no HTTP, no second remote call, just an Insert.
+    [EventSubscriber(ObjectType::Codeunit, Codeunit::"Sales-Post", 'OnAfterPostSalesDoc', '', false, false)]
+    local procedure StageShipmentNotification(var SalesHeader: Record "Sales Header")
+    var
+        IntegrationMessage: Record "Integration Message";
+    begin
+        // Only notify on an actual posted shipment, not on every posted document kind.
+        if not SalesHeader.Ship then
+            exit;
+
+        IntegrationMessage.Init();
+        IntegrationMessage."Message ID" := CreateGuid();
+        // Direction Outbound + Status New is exactly what the Job Queue processor queries for.
+        IntegrationMessage.Direction := IntegrationMessage.Direction::Outbound;
+        IntegrationMessage.Status := IntegrationMessage.Status::New;
+        IntegrationMessage.Type := 'SHIPMENT-NOTIFY';
+        // Carry the document ANCHOR, not a live handle. The processor re-reads detail later.
+        IntegrationMessage."Document No." := SalesHeader."No.";
+        IntegrationMessage."External Reference" := SalesHeader."External Document No.";
+        // Correlation id threads this notification to the rest of the flow's log lines.
+        IntegrationMessage."Correlation ID" := CopyStr(DelChr(LowerCase(Format(CreateGuid())), '=', '{}'), 1, 40);
+        // Insert participates in the posting transaction: the row lives only if the post commits,
+        // and rolls back cleanly with the post if posting fails. No remote system is touched here.
+        IntegrationMessage.Insert(true);
+    end;
+}
+
+codeunit 50111 "Outbound Sender"
+{
+    // Runs as a Job Queue entry, well after posting has committed and released its locks.
+    // Nothing it does can lengthen a posting lock window, because there is no longer a post in flight.
+    procedure SendNew()
+    var
+        IntegrationMessage: Record "Integration Message";
+    begin
+        IntegrationMessage.SetRange(Direction, IntegrationMessage.Direction::Outbound);
+        IntegrationMessage.SetRange(Status, IntegrationMessage.Status::New);
+        if IntegrationMessage.FindSet() then
+            repeat
+                // Each row is its own short unit of work. A slow endpoint stalls delivery
+                // of THIS message only; it cannot stall anyone's posting.
+                SendOne(IntegrationMessage);
+            until IntegrationMessage.Next() = 0;
+    end;
+
+    local procedure SendOne(var IntegrationMessage: Record "Integration Message")
+    var
+        Client: HttpClient;
+        Content: HttpContent;
+        Response: HttpResponseMessage;
+    begin
+        Content.WriteFrom(BuildShipmentJson(IntegrationMessage));
+        if Client.Post(GetEndpoint(IntegrationMessage), Content, Response) and Response.IsSuccessStatusCode() then begin
+            IntegrationMessage.Status := IntegrationMessage.Status::Resolved;
+            IntegrationMessage.Modify(true);
+        end else begin
+            // A failure here is recorded on the row and retried later. The posted shipment
+            // is already durable, so a WMS outage never costs us the posting.
+            IntegrationMessage."Retry Count" += 1;
+            IntegrationMessage."Error Message" := CopyStr(GetLastErrorText(), 1, 2048);
+            IntegrationMessage.Modify(true);
+        end;
+    end;
+}