feat: scale down prefect 0 resources and agents in helm values

[Winzen]

Closes #138

Resumo

• Reduz requests de CPU/memória dos componentes do Prefect 0 (hasura, graphql, apollo, towel, ui) para valores compatíveis com o uso real
• Zera réplicas do agent no chart do servidor e nos 3 namespaces de agentes (basedosdados, basedosdados-perguntas, basedosdados-projetos)
• Evita reversão das mudanças já aplicadas via kubectl em caso de helm upgrade

Mudanças

Arquivo	Alteração
k8s/prefect/chart/values.yaml	Reduz requests de hasura/graphql/apollo; graphql e apollo: 2→1 réplica; agent: 1→0 réplica; towel e ui: adiciona requests mínimos
k8s/prefect_agents/basedosdados/chart/values.yaml	replicas: 1 → 0
k8s/prefect_agents/basedosdados-perguntas/chart/values.yaml	replicas: 1 → 0
k8s/prefect_agents/basedosdados-projetos/chart/values.yaml	replicas: 1 → 0

Recursos liberados

~1.35 cores CPU + ~1.7Gi memória de requests devolvidos ao scheduler do cluster.

Test plan

• Verificar que helm upgrade com os novos values não reinicia pods com recursos maiores
• Confirmar que pods do Prefect 0 continuam rodando (apenas com resources menores, não deletados)
• Confirmar que agentes continuam em 0 réplicas após o upgrade

[github-actions]

💰 Infracost report

Monthly estimate increased by $0.06 📈

Changed project	Baseline cost	Usage cost*	Total change	New monthly cost
basedosdados/iac/terraform	+$0.06	-	+$0.06 (0%)	$458

*Usage costs can be estimated by updating Infracost Cloud settings, see docs for other options.

Estimate details

Key: * usage cost, ~ changed, + added, - removed

──────────────────────────────────
Project: main

+ module.cloudsql.google_secret_manager_secret_version.prefect3_db_password
  +$0.06

    + Active secret versions
      +$0.06

    + Access operations
      Monthly cost depends on usage
        +$0.03 per 10K requests

+ module.cloudsql.google_secret_manager_secret.prefect3_db_password
  Monthly cost depends on usage

    + Active secret versions
      Monthly cost depends on usage
        +$0.06 per versions

    + Access operations
      Monthly cost depends on usage
        +$0.03 per 10K requests

    + Rotation notifications
      Monthly cost depends on usage
        +$0.05 per rotations

Monthly cost change for basedosdados/iac/terraform
Amount:  +$0.06 ($458 → $458)
Percent: 0%

──────────────────────────────────
Key: * usage cost, ~ changed, + added, - removed

*Usage costs can be estimated by updating Infracost Cloud settings, see docs for other options.

32 cloud resources were detected:
∙ 14 were estimated
∙ 18 were free

Infracost estimate: Monthly estimate increased by $0.06 ↑
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┓
┃ Changed project                                    ┃ Baseline cost ┃ Usage cost* ┃ Total change ┃
┣━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━╋━━━━━━━━━━━━━━┫
┃ basedosdados/iac/terraform                         ┃        +$0.06 ┃           - ┃  +$0.06 (0%) ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━┻━━━━━━━━━━━━━━┛

_{This comment will be updated when code changes.}