fix(portal): typecheck error in scheduling (TS18048)

timeToMin destructured [h, m] from t.split(':').map(Number); under
noUncheckedIndexedAccess those are number|undefined, so `h * 60` errored. Use
default-value destructuring ([h = 0, m = 0]). Surfaced now that the Gitea runner
actually runs the typecheck job (it never ran before).

apps/portal/pages/admin/scheduling.vue

@@ -266,7 +266,7 @@ function addOverride() {
 function removeOverride(idx: number) {
   availForm.overrides.splice(idx, 1)
 }
-const timeToMin = (t: string) => { const [h, m] = t.split(':').map(Number); return h * 60 + m }
+const timeToMin = (t: string) => { const [h = 0, m = 0] = t.split(':').map(Number); return h * 60 + m }
 async function submitAvail() {
   if (!selectedHostId.value) return
   availBusy.value = true