fix(express): show Tax on totals + add tooling as real SO line

Three related fixes on the Express Orders totals card:

1. Totals card now breaks out Subtotal / Tax / Tooling Charge /
   Grand Total. Previously the "Subtotal" and "Grand Total" rows
   both read from total_amount (same value rendered twice) and no
   tax was shown at all. Customers on a fiscal position-mapped
   tax rate (Ontario HST, etc.) had their taxes silently dropped
   from the preview.

2. tooling_charge now feeds the Grand Total. The total_amount
   compute previously summed line subtotals only. Added a real
   SO line for the tooling charge in action_create_order so the
   eventual sale.order.amount_total matches the preview AND the
   invoice carries a "Tooling Charge" line item.

3. tax_ids is now visible as an optional column on the lines
   list. Operator can see + override the auto-applied tax per
   line. Default still comes from FP-SERVICE product mapped
   through partner.property_account_position_id (fiscal position).

New compute fields on fp.direct.order.wizard:
  - total_subtotal (sum of line.qty * line.unit_price, pre-tax)
  - total_tax (sum of line + tooling taxes via compute_all)
  - total_amount (subtotal + tax + tooling — was just subtotal)

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

fusion_plating/fusion_plating_configurator/__manifest__.py

@@ -5,7 +5,7 @@
 
 {
     'name': 'Fusion Plating — Configurator',
-    'version': '19.0.22.5.0',
+    'version': '19.0.22.6.0',
     'category': 'Manufacturing/Plating',
     'summary': 'Quotation configurator with part catalog, coating configs, and formula-based pricing engine.',
     'description': """