feat(configurator): "PO Pending" escape hatch for customers who send PO later

Customer feedback: some customers don't send their PO with the
initial order — they send it days or weeks later. The system was
blocking SO confirmation without a PO, which forced the shop to
either wait on paperwork or ask a manager for a formal override.

New estimator-level path: a "PO Pending" boolean on sale.order +
an optional "PO Expected By" date.

  * Confirm without a PO# / PO document when PO Pending is ticked.
  * action_confirm skips the hard error if po_pending OR po_override
    is set (keeps the existing manager-override path too).
  * On confirm with PO Pending, the system schedules a chase
    activity for po_expected_date (or +3 days if blank), assigned
    via mail.activity so it shows up in the sales user's activity
    list. Chatter note logged so audit is obvious.
  * Direct-order wizard: po_number and po_attachment_file become
    optional. Ticking "PO Pending" in the wizard is the trade-in;
    a help note under the toggle explains the chase behaviour.
  * Once the PO arrives, user fills in the PO# / uploads the doc,
    and turns PO Pending off — existing downstream flow resumes.

Difference from x_fc_po_override (kept):
  * PO Override = manager waiver, permanent ("handshake deal").
  * PO Pending = estimator flag, time-boxed ("customer will send it
    by Friday").

fusion_plating_configurator → 19.0.14.0.0
fusion_plating_invoicing    → 19.0.3.0.0

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

fusion_plating/fusion_plating_invoicing/models/sale_order.py

@@ -31,23 +31,36 @@ class SaleOrder(models.Model):
         """Override to check account hold + customer PO# and trigger
         the invoice strategy."""
         for order in self:
-            # --- Customer PO# required ---
+            # --- Customer PO# required (with escape hatches) ---
             # Aerospace AP teams reject invoices without their PO#
             # quoted back. Catching this at SO confirm prevents the
             # whole downstream chain (CoC, BoL, invoice) from going
             # out unreferenced. The PO# is on `client_order_ref`
             # (Odoo standard) AND mirrored to `x_fc_po_number`
             # (FP-specific) — accept either as filled.
+            #
+            # Two escape hatches for real-world cases:
+            #   * x_fc_po_pending — estimator flag: "PO coming later".
+            #     Confirms the order without a PO number and schedules
+            #     a chase activity for x_fc_po_expected_date so sales
+            #     doesn't forget to chase the paperwork.
+            #   * x_fc_po_override — manager waiver: "proceed without
+            #     a formal PO (handshake deal)". Permanent.
             po_set = bool(order.client_order_ref) or bool(
                 getattr(order, 'x_fc_po_number', False)
             )
-            if not po_set:
+            po_pending = bool(getattr(order, 'x_fc_po_pending', False))
+            po_override = bool(getattr(order, 'x_fc_po_override', False))
+            if not po_set and not po_pending and not po_override:
                 raise UserError(_(
                     'Cannot confirm SO "%(so)s" — Customer PO# is required.\n\n'
                     'Set the customer\'s purchase order number in the '
                     '"Customer Reference" field (or x_fc_po_number) before '
-                    'confirming. Aerospace customers\' AP teams reject '
-                    'invoices that don\'t quote their PO# back.'
+                    'confirming. If the customer will provide the PO '
+                    'later, tick "PO Pending" and set "PO Expected By" — '
+                    'the order will confirm with a follow-up activity to '
+                    'chase the paperwork. A Plating Manager can also set '
+                    '"PO Override" for handshake deals.'
                 ) % {'so': order.name})
 
             # --- Account hold check ---
@@ -73,6 +86,36 @@ class SaleOrder(models.Model):
 
         res = super().action_confirm()
 
+        # --- PO-pending chase activity ---
+        # Sales team needs to chase the customer for the real PO before
+        # any invoice goes out. Schedule a follow-up on the expected
+        # date (or 3 days out if unset).
+        for order in self:
+            if not getattr(order, 'x_fc_po_pending', False):
+                continue
+            if getattr(order, 'x_fc_po_number', False) or order.client_order_ref:
+                continue  # PO already set — nothing to chase
+            from datetime import timedelta
+            expected = (
+                order.x_fc_po_expected_date
+                or (fields.Date.context_today(order) + timedelta(days=3))
+            )
+            order.activity_schedule(
+                'mail.mail_activity_data_todo',
+                date_deadline=expected,
+                summary=_('Chase customer PO for %s') % order.name,
+                note=_(
+                    'Order confirmed with PO Pending. Follow up with '
+                    '%(partner)s for their PO number (and PDF if '
+                    'available), then tick PO Pending off and enter the '
+                    'PO# on the sale order.'
+                ) % {'partner': order.partner_id.display_name},
+            )
+            order.message_post(body=_(
+                'Order confirmed without PO. Chase activity scheduled '
+                'for %(date)s.'
+            ) % {'date': expected.strftime('%Y-%m-%d')})
+
         # --- Invoice strategy automation (on confirm) ---
         for order in self:
             strategy = order.x_fc_invoice_strategy