feat(portal): per-stage timestamps on fp.portal.job

Adds received_at, in_progress_started_at, qc_started_at,
ready_to_ship_at, shipped_at - snapshotted on state change via
write() override using super().write() to avoid recursion. Required
for the vertical-timeline rendering on the job detail page (Phase 3).

Idempotent: re-transitioning to a state already-stamped does not
overwrite the original timestamp.

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

fusion_plating/fusion_plating_portal/tests/test_portal_dashboard.py

@@ -57,3 +57,20 @@ class TestPortalDashboard(TransactionCase):
         self.assertEqual(active, 2)
         self.assertEqual(awaiting_review, 1)
         self.assertEqual(ready_to_ship, 1)
+
+    def test_state_change_snapshots_timestamp(self):
+        """write({'state': 'in_progress'}) sets in_progress_started_at."""
+        from odoo import fields as odoo_fields
+        Job = self.env['fusion.plating.portal.job']
+        job = Job.create({
+            'name': 'WO-TS-001',
+            'partner_id': self.partner.id,
+            'state': 'received',
+        })
+        self.assertTrue(job.received_at, 'received_at set on create')
+        before = odoo_fields.Datetime.now()
+        job.state = 'in_progress'
+        self.assertTrue(job.in_progress_started_at, 'in_progress_started_at set')
+        self.assertGreaterEqual(job.in_progress_started_at, before)
+        # received_at must not be overwritten when state advances
+        self.assertTrue(job.received_at)