feat(admin): add POST /api/admin/alerts/dismiss endpoint

server/api/admin/alerts/dismiss.post.js

@@ -0,0 +1,16 @@
+import AdminAlertDismissal from '../../../models/adminAlertDismissal.js'
+import { connectDB } from '../../../utils/mongoose.js'
+
+export default defineEventHandler(async (event) => {
+  const admin = await requireAdmin(event)
+  const { alertType, signature } = await validateBody(event, adminAlertDismissSchema)
+  await connectDB()
+
+  await AdminAlertDismissal.findOneAndUpdate(
+    { adminId: admin._id.toString(), alertType },
+    { $set: { signature, dismissedAt: new Date() } },
+    { upsert: true, new: true }
+  )
+
+  return { ok: true }
+})