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>

convex/deviceFieldDefaults.ts

@@ -73,11 +73,11 @@ export async function ensureMobileDeviceFields(ctx: MutationCtx, tenantId: strin
   const existingMobileFields = await ctx.db
     .query("deviceFields")
     .withIndex("by_tenant_scope", (q) => q.eq("tenantId", tenantId).eq("scope", "mobile"))
-    .collect();
+    .take(100);
   const allFields = await ctx.db
     .query("deviceFields")
     .withIndex("by_tenant_order", (q) => q.eq("tenantId", tenantId))
-    .collect();
+    .take(100);
 
   const existingByKey = new Map<string, Doc<"deviceFields">>();
   existingMobileFields.forEach((field) => existingByKey.set(field.key, field));