settings UI: add Site Base URL + Alert Webhook URL/format fields

The webhook + site_base_url settings existed in the backend but the Email
Settings page had no inputs (hardcoded fields), and the settings composable's
reactive map didn't include the keys so they never loaded. Add the three inputs
(site base URL, webhook URL, webhook format select) and register the keys.

frontend/src/composables/systemSettings.js

@@ -108,6 +108,9 @@ export function useSystemSettings() {
     smtp_from_address: '',
     smtp_from_name: 'ShopDB',
     alert_recipients: '',
+    site_base_url: '',
+    alert_webhook_url: '',
+    alert_webhook_format: 'teams',
     // Audit
     audit_retention_days: 90,
     // Floor map blueprint (per-facility)

frontend/src/views/settings/EmailSettings.vue

@@ -137,6 +137,50 @@
             </label>
           </div>
 
+          <div class="setting-row full-width">
+            <label>
+              <span>Site Base URL</span>
+              <input
+                type="text"
+                v-model="settings.site_base_url"
+                placeholder="https://tsgwp00525.wjs.geaerospace.net/ops"
+                @blur="saveSetting('site_base_url', settings.site_base_url)"
+                :disabled="saving"
+              >
+              <small class="input-hint">Public URL of this site; used to build links in emails</small>
+            </label>
+          </div>
+
+          <div class="setting-row full-width">
+            <label>
+              <span>Alert Webhook URL</span>
+              <input
+                type="text"
+                v-model="settings.alert_webhook_url"
+                placeholder="https://...  (Microsoft Teams Incoming Webhook or Workflow)"
+                @blur="saveSetting('alert_webhook_url', settings.alert_webhook_url)"
+                :disabled="saving"
+              >
+              <small class="input-hint">Alerts also POST here (Teams, etc.). Blank = email only.</small>
+            </label>
+          </div>
+
+          <div class="setting-row full-width">
+            <label>
+              <span>Alert Webhook Format</span>
+              <select
+                v-model="settings.alert_webhook_format"
+                @change="saveSetting('alert_webhook_format', settings.alert_webhook_format)"
+                :disabled="saving"
+              >
+                <option value="teams">Teams - Incoming Webhook (MessageCard)</option>
+                <option value="adaptivecard">Teams - Workflow (Adaptive Card)</option>
+                <option value="json">Generic JSON</option>
+              </select>
+              <small class="input-hint">Payload format for the webhook above</small>
+            </label>
+          </div>
+
           <div class="status-indicator">
             <span class="status-dot" :class="smtpStatus"></span>
             <span>{{ smtpMessage }}</span>