feat(jobs): Phase 6 — Process Tree OWL component for fp.job

Ports fusion_plating_shopfloor's process_tree.js to bind to fp.job
instead of mrp.production. Consumes the /fp/jobs/process_tree
JSON endpoint built in Phase 6 lean.

Renders the recipe tree as cards. Each operation card shows the
step state (pending/ready/in_progress/done/etc.) when there's a
matching fp.job.step. Click an operation card -> open the step
form. Click Back -> return to the job form.

New 'Process Tree' button on the fp.job form (manager-only)
launches the client action with job_id context.

Manifest 19.0.2.1.0 -> 19.0.2.2.0.

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_jobs/models/fp_job.py

@@ -253,6 +253,26 @@ class FpJob(models.Model):
                 )
         return True
 
+    # ------------------------------------------------------------------
+    # UI — Process Tree client action (Phase 6)
+    # ------------------------------------------------------------------
+    def action_open_process_tree(self):
+        """Open the OWL process-tree visualization for this job.
+
+        Launches the fp_job_process_tree client action with job_id in
+        context. The component fetches /fp/jobs/process_tree and renders
+        the recipe -> sub_process -> operation hierarchy as cards with
+        per-step state badges.
+        """
+        self.ensure_one()
+        return {
+            'type': 'ir.actions.client',
+            'tag': 'fp_job_process_tree',
+            'context': {'job_id': self.id},
+            'name': 'Process Tree — %s' % (self.name or ''),
+            'target': 'current',
+        }
+
     # ------------------------------------------------------------------
     # Lifecycle hooks (Tasks 2.6, 2.7, 2.8)
     #