chore: bump DIR components to v0.5.5

[tkircsi]

Description

Updates the dir-staging example deployment from v0.5.2 to v0.5.5.

Changes

• Version bump: DIR apiserver and CLI to v0.5.5
• SPIFFE CSI driver: Enable useCSIDriver: true for both dir and dir-admin
  • Provides synchronous workload identity injection
  • Eliminates "certificate contains no URI SAN" authentication failures
• OASF validation: Add oasf_api_validation_strict_mode: false (lax mode)
  • Allows validation warnings for non-standard OASF modules
• Documentation: Updated README and CHANGELOG

Compatibility

• ✅ Kind clusters (Kubernetes 1.16+)
• ✅ Minikube clusters
• ✅ SPIRE Helm chart v0.27.0 (includes CSI driver by default)

Type of Change

• Other: Version bump with new features

Checklist

• I have read the contributing guidelines
• I have verified this change is not present in other open pull requests
• Functionality is documented
• All code style checks pass