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-source-table-is-temporary.md

@@ -0,0 +1,30 @@
+---
+bc-version: [27..]
+domain: agents
+keywords: [sourcetabletemporary, configurationdialog, savechanges, cancel, draft]
+technologies: [al]
+countries: [w1]
+application-area: [all]
+---
+
+# Keep the agent setup page source temporary until Update
+
+## Description
+
+ConfigurationDialog setup is a draft: the user can Cancel without writing. That only works if `SourceTableTemporary = true` and custom fields stay in memory until Update. Writing the real table in OnValidate or OnOpenPage commits a partial agent when the dialog errors or is cancelled.
+
+## Best Practice
+
+Mark the page `SourceTableTemporary = true`. Copy into the temp record on open. Persist the Agent Setup buffer and custom fields only from the close path when the action is not Cancel, using `Agent Setup.GetChangesMade` / `SaveChanges`.
+
+See sample: `agent-setup-source-table-is-temporary.good.al`.
+
+## Anti Pattern
+
+A non-temporary source table, or `Insert`/`Modify` on the persisted setup row from field OnValidate. Detection signal: agent `ConfigurationDialog` without `SourceTableTemporary = true`, or database writes before Update.
+
+See sample: `agent-setup-source-table-is-temporary.bad.al`.
+
+## See also
+
+`agent-setup-page-is-configuration-dialog.md` defines the setup page shape that uses this draft lifecycle.