Employees + USB default-disabled with an enable-time provisioning note

Both plugins provision extra tables, so they now install disabled and explain
themselves before a site opts in.

- Plugin contract gains get_provisioning_note() -> {tables, note, docs}.
  Employees and USB implement it (what tables get created in shopdb, how they
  are referenced, link to the schema README; USB references the captured
  DLP/reminder plans).
- Manifest default_enabled=false for employees + usb; the plugins list API
  returns provisioning_note + default_enabled; install now registers a plugin
  disabled when default_enabled is false.
- Setup wizard Features step renders the provisioning note the moment a plugin
  with one is enabled.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/employees/plugin.py

@@ -60,6 +60,20 @@ class EmployeesPlugin(BasePlugin):
         External mode reads a separate DB via employee_connection instead."""
         return [DirectoryEmployee]
 
+    def get_provisioning_note(self) -> Optional[Dict]:
+        return {
+            'tables': ['directoryemployees'],
+            'note': ('Enabling this in self-hosted mode creates a '
+                     '"directoryemployees" table in the shopdb database (SSO, '
+                     'First_Name, Last_Name, Team, Role, Picture). It is '
+                     'referenced across the site: employee search, notification '
+                     'recognition (name + photo on the shopfloor/lobby displays), '
+                     'and USB check-in/out name resolution. Manage people under '
+                     'Settings > Employee Directory, or point at an existing HR '
+                     'database instead (external mode).'),
+            'docs': 'plugins/employees/README.md',
+        }
+
     def get_config_schema(self) -> List[Dict]:
         """Employee directory DB connection. Host/name/user are settings the
         wizard can edit; the password stays in .env (emitted, not stored)."""