feat(jobs): cutover - bridge_mrp gate, menu nesting, migration robustness

Three changes to support live cutover on entech (2026-04-25):

1. Bridge_mrp gate: sale.order.action_confirm in
   fusion_plating_bridge_mrp now skips _fp_auto_create_mo when the
   x_fc_use_native_jobs config flag is True. Without this, every SO
   confirm would create both an mrp.production AND an fp.job
   (duplicate work). The gate is the only modification to bridge_mrp
   during the migration — the rest stays untouched.

2. Menu nesting: Plating Jobs (Native) now lives INSIDE the existing
   Plating app (parent=menu_fp_root) instead of as a separate
   top-level app. Two parallel 'Plating' apps was confusing UX. Work
   Centres (Native) goes under the existing Configuration sub-menu.
   '(Native)' suffix is temporary — drops at full legacy removal.

3. Migration script robustness: per-MO savepoints (so one bad MO
   doesn't abort the whole transaction with cascading 'transaction
   aborted' errors) + extended partner resolver fallback chain
   (warehouse partner → company partner) for orphan demo MOs without
   SO link or x_fc_customer_id. Verified: 43 MOs + 297 WOs migrated
   on entech with 0 errors after these fixes.

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_bridge_mrp/models/sale_order.py

@@ -81,6 +81,13 @@ class SaleOrder(models.Model):
     # ------------------------------------------------------------------
     def action_confirm(self):
         res = super().action_confirm()
+        # Cutover gate (2026-04-25): when the native job model is the
+        # primary, skip MO creation here — fusion_plating_jobs handles
+        # SO → fp.job. Both modules' SO-confirm hooks would otherwise
+        # run on every confirm and create duplicate work.
+        ICP = self.env['ir.config_parameter'].sudo()
+        if ICP.get_param('fusion_plating_jobs.use_native_jobs') == 'True':
+            return res
         for so in self:
             try:
                 so._fp_auto_create_mo()