Add community guidance and review support for Business Central agents (#137)

* feat(community/agents): add AL agent quality guidance

- add 20 agent knowledge rules with good and bad AL samples
- clarify setup dialog shape, temporary persistence, permissions, profiles, instructions, capability registration, and interface wiring
- add the community-owned AL agents review skill
- make review fixture discovery layer-aware with custom, community, and Microsoft precedence
- document layer-aware evaluation behavior

* fix(community/agents): align setup and permission samples

- mark agent setup pages as non-extensible where required
- narrow the agent profile by hiding an unrelated sales-order field
- define a dedicated read-only permission set for the sales review agent
- assign AL-defined permission sets with system scope and the owning app ID
- clarify the permission scope guidance for default access controls

* Address agent review feedback

community/knowledge/agents/get-default-access-controls-least-privilege.good.al

@@ -0,0 +1,25 @@
+permissionset 50100 "SALES REVIEW AGENT"
+{
+    Assignable = true;
+    Caption = 'Sales Review Agent';
+    Permissions =
+        tabledata "Sales Header" = R,
+        tabledata "Sales Line" = R;
+}
+
+codeunit 50100 "Sales Review Agent Factory"
+{
+    procedure GetDefaultAccessControls(var TempAccessControlBuffer: Record "Access Control Buffer" temporary)
+    var
+        CurrentModuleInfo: ModuleInfo;
+        RoleIdTok: Label 'SALES REVIEW AGENT', Locked = true;
+    begin
+        NavApp.GetCurrentModuleInfo(CurrentModuleInfo);
+        Clear(TempAccessControlBuffer);
+        TempAccessControlBuffer."Company Name" := CopyStr(CompanyName(), 1, MaxStrLen(TempAccessControlBuffer."Company Name"));
+        TempAccessControlBuffer.Scope := TempAccessControlBuffer.Scope::System;
+        TempAccessControlBuffer."App ID" := CurrentModuleInfo.Id;
+        TempAccessControlBuffer."Role ID" := RoleIdTok;
+        TempAccessControlBuffer.Insert();
+    end;
+}