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

evaluation/review-fixtures.json

@@ -4,6 +4,9 @@
   "minimumExpectedRecall": 1.0,
   "minimumCleanRate": 1.0,
   "overrides": {
+    "agents": {
+      "article": "wire-all-three-agent-interfaces"
+    },
     "appsource": {
       "context": "AppSourceCop mandatoryAffixes is configured to ABC."
     },