alerts: per-support-team webhook; printedparts routes low-stock to a chosen team

Support teams gain a webhookurl (migration 7d29 + API + settings-page field), so
a team is a notification target. send_webhook(url=) lets a caller override the
site default with a team's webhook. Printedparts gains a 'alert support team'
setting (printedparts_alert_supportteamid) + selector on its settings page;
low-stock alerts post to that team's webhook, falling back to the site
alert_webhook_url. Email leg unchanged. Same pattern extends to other alerting
plugins (printers low-toner next).

plugins/printedparts/api/routes.py

@@ -330,7 +330,7 @@ def _send_lowstock_alert(item):
     Recipients: Setting printedparts_alert_email (comma-separated), falling
     back to the site's alert_recipients. Never fails the transaction - the
     ledger write already committed."""
-    from shopdb.api import send_email, send_alert, send_webhook, Setting
+    from shopdb.api import send_email, send_webhook, Setting
     code = item.gagelabtag or item.itemcode
     subject = (f'Low stock: {item.itemname} ({code}) - '
                f'{item.quantityonhand} left')
@@ -350,20 +350,43 @@ def _send_lowstock_alert(item):
                     f'Bin: {item.binlocation or "-"}.'
                     + (f' [View]({item_url})' if item_url else ''))
     try:
-        recipients = _alert_recipients()
+        # Webhook: the selected support team's own webhook, else the site
+        # default (send_webhook falls back to alert_webhook_url when url=None).
+        send_webhook(subject, webhook_text, url=_alert_team_webhook())
+        # Email: this plugin's recipients, else the site's alert_recipients.
+        recipients = _alert_recipients() or _site_alert_recipients()
         if recipients:
-            # send_email does not fan to the webhook, so post it explicitly.
-            send_webhook(subject, webhook_text)
             send_email(recipients, subject, html)
-        else:
-            # send_alert already fans out to email + webhook.
-            send_alert(subject, html)
     except Exception:
         import logging
         logging.getLogger(__name__).exception(
             'Low-stock alert failed for %s', item.itemcode)
 
 
+def _site_alert_recipients():
+    """Site-wide alert_recipients setting as a clean list (email fallback)."""
+    from shopdb.api import Setting
+    raw = Setting.get('alert_recipients') or ''
+    return [r.strip() for r in raw.replace(';', ',').split(',') if r.strip()]
+
+
+def _alert_team_webhook():
+    """Webhook URL of the support team chosen for printedparts alerts, or None.
+
+    printedparts_alert_supportteamid selects a SupportTeam; alerts route to that
+    team's webhook. None -> send_webhook uses the site-wide default."""
+    from shopdb.api import Setting
+    team_id = Setting.get('printedparts_alert_supportteamid')
+    if not team_id:
+        return None
+    try:
+        from shopdb.core.models import SupportTeam
+        team = db.session.get(SupportTeam, int(team_id))
+    except (ValueError, TypeError):
+        return None
+    return (team.webhookurl or None) if team else None
+
+
 @printedparts_bp.route('/items/<int:item_id>/restock', methods=['POST'])
 @jwt_required()
 @require_permission('printedparts.restock')