fix(convex): corrigir memory leak com .collect() sem limite e adicionar otimizacoes

Problema: Convex backend consumindo 16GB+ de RAM causando OOM kills

Correcoes aplicadas:
- Substituido todos os .collect() por .take(LIMIT) em 27+ arquivos
- Adicionado indice by_usbPolicyStatus para otimizar query de maquinas
- Corrigido N+1 problem em alerts.ts usando Map lookup
- Corrigido full table scan em usbPolicy.ts
- Corrigido subscription leaks no frontend (tickets-view, use-ticket-categories)
- Atualizado versao do Convex backend para precompiled-2025-12-04-cc6af4c

Arquivos principais modificados:
- convex/*.ts - limites em todas as queries .collect()
- convex/schema.ts - novo indice by_usbPolicyStatus
- convex/alerts.ts - N+1 fix com Map
- convex/usbPolicy.ts - uso do novo indice
- src/components/tickets/tickets-view.tsx - skip condicional
- src/hooks/use-ticket-categories.ts - skip condicional

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/hooks/use-ticket-categories.ts

@@ -6,7 +6,10 @@ import { api } from "@/convex/_generated/api"
 import type { TicketCategory } from "@/lib/schemas/category"
 
 export function useTicketCategories(tenantId: string) {
-  const categories = useQuery(api.categories.list, { tenantId }) as TicketCategory[] | undefined
+  const categories = useQuery(
+    api.categories.list,
+    tenantId ? { tenantId } : "skip"
+  ) as TicketCategory[] | undefined
   const ensureDefaults = useMutation(api.categories.ensureDefaults)
   const initializingRef = useRef(false)