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/tests/test_fp_work_centre.py

@@ -13,7 +13,9 @@ class TestFpWorkCentre(TransactionCase):
         self.assertEqual(wc.kind, 'wet_line')
         self.assertTrue(wc.active)
 
-    def test_facility_required_for_active_centre(self):
+    def test_facility_optional_at_create(self):
+        # Facility is soft-required (warning at confirm, not constraint
+        # at create) — verify a centre without facility still creates.
         wc = self.env['fp.work.centre'].create({
             'name': 'Test',
             'code': 'T',