Feat/override all images

[ijustworkhereshrug]

Summary

Add override capability for repository and tag for alpine and busybox images (Fixes #143)

Test Checklist

• Helm template renders without errors
• Terraform validates/plans cleanly
• Manually verified on staging cluster (if applicable)
• Rollback strategy documented

Infrastructure

• Helm: helm template renders correctly
• Terraform: terraform validate passes
• Terraform: terraform plan shows expected changes
• ArgoCD: Application manifests are valid
• N/A - documentation only

[ijustworkhereshrug]

@brandonrc Let me know if this looks good! Thanks