docs(jobs): tighten spec/plan after Task 1.2 review

- Spec §5.3: document that default_oven_id is deferred to the
  fusion_plating_jobs bridge module (fusion.plating.bake.oven lives
  in shopfloor; core can't depend on it).
- Plan: align ACL blocks for Tasks 1.2/1.3/1.5/1.7 to use
  group_fusion_plating_operator for the lowest tier instead of
  base.group_user. Caught by the code-quality reviewer on Task 1.2;
  this prevents the same bug recurring in later tasks.
- Plan Task 1.2 test name corrected:
  test_facility_required_for_active_centre →
  test_facility_optional_at_create.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_plating/docs/superpowers/specs/2026-04-25-fp-native-job-model-design.md

@@ -220,7 +220,8 @@ domain-specific (a tank line, a bake oven, a rack station — not assembly cells
 | `facility_id` | Many2one(fp.facility) | Which facility |
 | `kind` | Selection | `wet_line`, `bake`, `mask`, `rack`, `inspect`, `other` |
 | `cost_per_hour` | Monetary | For margin calculations |
-| `default_bath_id, default_tank_id, default_oven_id` | Many2one | Single-line shop convenience |
+| `default_bath_id, default_tank_id` | Many2one(`fusion.plating.bath`/`.tank`) | Single-line shop convenience |
+| `default_oven_id` | Many2one(`fusion.plating.bake.oven`) | **Deferred to `fusion_plating_jobs` bridge module via `_inherit`** — `bake.oven` is defined in `fusion_plating_shopfloor` which `fusion_plating` core cannot depend on. Bridge module *can* depend on shopfloor and adds this field there. |
 | `active` | Boolean | |
 
 This replaces `x_fc_mrp_workcenter_id` mapping that the recipe operations have today.