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/agent-setup-table-keyed-by-user-security-id.good.al

@@ -0,0 +1,25 @@
+table 50100 "Sales Review Agent Setup"
+{
+    DataClassification = CustomerContent;
+
+    fields
+    {
+        field(1; "User Security ID"; Guid)
+        {
+            Caption = 'User Security ID';
+            DataClassification = EndUserPseudonymousIdentifiers;
+        }
+        field(10; "Review Threshold"; Decimal)
+        {
+            Caption = 'Review Threshold';
+        }
+    }
+
+    keys
+    {
+        key(PK; "User Security ID")
+        {
+            Clustered = true;
+        }
+    }
+}