refactor(jobs): address code review feedback on fp.work.centre

- ACL: use group_fusion_plating_operator for read-only tier instead of
  base.group_user, matching the established hierarchy in the rest of
  ir.model.access.csv
- Test: rename test_facility_required_for_active_centre →
  test_facility_optional_at_create. Old name claimed the opposite of
  what the assertion checks.
- Manifest version bumped 19.0.8.1.0 → 19.0.8.1.1.

Part of: native job model migration (spec 2026-04-25)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating/__manifest__.py

@@ -5,7 +5,7 @@
 
 {
     'name': 'Fusion Plating',
-    'version': '19.0.8.1.0',
+    'version': '19.0.8.1.1',
     'category': 'Manufacturing/Plating',
     'summary': 'Core plating / metal finishing ERP: facilities, processes, tanks, baths, jobs, operators.',
     'description': """