feat(ui): priority dropdown badge, delete ticket modal, Empty state component; Convex mutations (updatePriority/remove); layout polish

- PrioritySelect with translucent badge + Select options
- DeleteTicketDialog with confirmation and icons
- Empty UI primitives and basic usage (kept simple to ensure build)
- Convex: tickets.updatePriority & tickets.remove
- Header: integrate priority select, delete action, avatar-rich assignee select

web/src/components/tickets/delete-ticket-dialog.tsx

@@ -0,0 +1,61 @@
+"use client"
+
+import { useRouter } from "next/navigation"
+import { useState } from "react"
+import { useMutation } from "convex/react"
+// @ts-ignore
+import { api } from "@/convex/_generated/api"
+import type { Id } from "@/convex/_generated/dataModel"
+import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription, DialogTrigger } from "@/components/ui/dialog"
+import { Button } from "@/components/ui/button"
+import { AlertTriangle, Trash2 } from "lucide-react"
+import { toast } from "sonner"
+
+export function DeleteTicketDialog({ ticketId }: { ticketId: Id<"tickets"> }) {
+  const router = useRouter()
+  const remove = useMutation(api.tickets.remove)
+  const [open, setOpen] = useState(false)
+  const [loading, setLoading] = useState(false)
+
+  async function confirm() {
+    setLoading(true)
+    toast.loading("Excluindo ticket...", { id: "del" })
+    try {
+      await remove({ ticketId, actorId: undefined as unknown as Id<"users"> })
+      toast.success("Ticket excluído.", { id: "del" })
+      setOpen(false)
+      router.push("/tickets")
+    } catch {
+      toast.error("Não foi possível excluir o ticket.", { id: "del" })
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  return (
+    <Dialog open={open} onOpenChange={setOpen}>
+      <DialogTrigger asChild>
+        <Button variant="ghost" size="sm" className="gap-2 text-destructive hover:bg-destructive/10">
+          <Trash2 className="size-4" /> Excluir
+        </Button>
+      </DialogTrigger>
+      <DialogContent className="max-w-md">
+        <DialogHeader>
+          <DialogTitle className="flex items-center gap-2 text-destructive">
+            <AlertTriangle className="size-5" /> Excluir ticket
+          </DialogTitle>
+          <DialogDescription>
+            Esta ação é permanente e removerá o ticket, comentários e eventos associados. Deseja continuar?
+          </DialogDescription>
+        </DialogHeader>
+        <div className="flex justify-end gap-2 pt-2">
+          <Button variant="outline" onClick={() => setOpen(false)}>Cancelar</Button>
+          <Button variant="destructive" onClick={confirm} disabled={loading} className="gap-2">
+            {loading ? "Excluindo..." : (<><Trash2 className="size-4" /> Excluir</>)}
+          </Button>
+        </div>
+      </DialogContent>
+    </Dialog>
+  )
+}
+