feat(jobs): add core-safe extension fields to fp.job

Scope was reduced from spec's full §5.1 list because 6 of the 10
plating-specific fields point to models in dependent modules
(configurator, quality, portal, logistics, bridge_mrp). Adding
those Many2ones in core would invert the dependency graph. They
move to their owning modules via _inherit = 'fp.job' and get
re-bundled by fusion_plating_jobs in Phase 2.

This commit lands the core-safe subset:
- sale_order_line_ids (sale_management is in core depends)
- recipe_id, start_at_node_id (process.node is in core)
- invoice_ids (account is reachable via sale_management → sale)
- Cost rollup: quoted_revenue / actual_cost / margin / margin_pct
  with placeholder compute (actual_cost = 0 until Task 1.5 wires
  fp.job.step.cost_total)
- current_location stub (full Bath/Oven rendering in Task 1.6)

Tests cover the cost-rollup math and the current_location stub.
Spec §5.1 has been re-tabulated with explicit 'Module' column.

Manifest 19.0.8.2.1 → 19.0.8.3.0.

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': '19.0.8.2.1',
+    'version': '19.0.8.3.0',
     'category': 'Manufacturing/Plating',
     'summary': 'Core plating / metal finishing ERP: facilities, processes, tanks, baths, jobs, operators.',
     'description': """