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

community/knowledge/agents/reapply-resource-instructions-on-upgrade.bad.al

@@ -0,0 +1,18 @@
+codeunit 50100 "Sales Review Agent Create"
+{
+    procedure CreateWithInstructions()
+    var
+        Agent: Codeunit Agent;
+        TempAgentAccessControl: Record "Agent Access Control" temporary;
+        AgentUserSecurityId: Guid;
+        InstructionsNameTxt: Label 'Instructions.txt', Locked = true;
+    begin
+        AgentUserSecurityId := Agent.Create(
+            Enum::"Agent Metadata Provider"::"Sales Review Agent",
+            'SALESREVIEW',
+            'Sales Review Agent',
+            TempAgentAccessControl);
+        // Only new instances get the resource. Upgrades never re-apply it.
+        Agent.SetInstructions(AgentUserSecurityId, NavApp.GetResourceAsText(InstructionsNameTxt));
+    end;
+}