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).

frontend/src/views/settings/SupportTeamsList.vue

@@ -63,6 +63,10 @@
               <label for="teamurl">Team URL</label>
               <input id="teamurl" v-model="teamForm.teamurl" type="text" class="form-control" placeholder="ServiceNow group link" />
             </div>
+            <div class="form-group">
+              <label for="webhookurl">Alert Webhook URL</label>
+              <input id="webhookurl" v-model="teamForm.webhookurl" type="text" class="form-control" placeholder="Microsoft Teams webhook for this team's alerts" />
+            </div>
             <div v-if="teamError" class="error-message">{{ teamError }}</div>
           </div>
           <div class="modal-footer">
@@ -202,7 +206,7 @@ function contactEmail(contact) {
 const showTeamModal = ref(false)
 const editingTeam = ref(null)
 const teamError = ref('')
-const teamForm = ref({ teamname: '', teamurl: '' })
+const teamForm = ref({ teamname: '', teamurl: '', webhookurl: '' })
 
 const showContactModal = ref(false)
 const editingContact = ref(null)
@@ -238,8 +242,8 @@ function openContactsModal(team) {
 function openTeamModal(team = null) {
   editingTeam.value = team
   teamForm.value = team
-    ? { teamname: team.teamname || '', teamurl: team.teamurl || '' }
-    : { teamname: '', teamurl: '' }
+    ? { teamname: team.teamname || '', teamurl: team.teamurl || '', webhookurl: team.webhookurl || '' }
+    : { teamname: '', teamurl: '', webhookurl: '' }
   teamError.value = ''
   showTeamModal.value = true
 }
@@ -250,7 +254,8 @@ async function saveTeam() {
   try {
     const payload = {
       teamname: teamForm.value.teamname,
-      teamurl: teamForm.value.teamurl || null
+      teamurl: teamForm.value.teamurl || null,
+      webhookurl: teamForm.value.webhookurl || null
     }
     if (editingTeam.value) {
       await supportteamsApi.update(editingTeam.value.supportteamid, payload)