feat: Core Plugin system — is_core flag, topological sort dependency resolution, deactivation protection

app/plugins/builtins/entity_links/plugin.py

@@ -37,6 +37,7 @@ class EntityLinksPlugin(BasePlugin):
         events=["company.deleted", "contact.deleted"],
         migrations=["0001_initial.sql"],
         permissions=[],
+        is_core=True,
     )
 
     async def on_company_deleted(self, payload: dict[str, Any]) -> None:

app/plugins/builtins/permissions/plugin.py

@@ -30,4 +30,5 @@ class PermissionsPlugin(BasePlugin):
         events=[],
         migrations=["0001_initial.sql"],
         permissions=[],
+        is_core=True,
     )

app/plugins/builtins/tags/plugin.py

@@ -25,4 +25,5 @@ class TagsPlugin(BasePlugin):
         events=[],
         migrations=["0001_initial.sql"],
         permissions=[],
+        is_core=True,
     )