feat(content): add GLPI 12.0.0-rc1 announcement blog post (pt-br and en)

[eduardofraga]

Summary

Announces the release of GLPI 12.0.0-rc1 and Helm Chart 2.12.0 from EF-TECH in both Portuguese and English.

Key Highlights Covered

• Modernized subcharts: replaced inline Redis with helmforge/valkey and inline MariaDB with helmforge/mariadb
• Added externalCache support for external Valkey/Redis clusters
• High availability & scalability: optional PodDisruptionBudget and HorizontalPodAutoscaler for php-fpm and nginx
• Kubernetes workload scheduling with priorityClassName support
• Security hardening: empirically verified readOnlyRootFilesystem: true, database password read from subchart secret, existingSecret support for external database with fast-fail validation
• S3-compatible files backup CronJob
• Readiness-gated maintenance CronJob
• Bitnami-style resource presets (resourcesPreset)
• Helm repository structure reorganization under helm/ with Artifact Hub validation

Artifacts Included

• content/pt-br/blog/glpi-12-0-0-rc1.md
• content/en/blog/glpi-12-0-0-rc1.md
• static/img/blog/glpi-12-0-0-rc1/cover.png (1200x630 OG image)
• static/img/blog/glpi-12-0-0-rc1/generate_cover.py
• Cross-references in .context/docs/README.md, .context/agents/README.md, and .context/plans/

Validation

• Local Hugo build passed (hugo --gc --minify)
• Lychee link checker passed with 0 broken links