🤖 ci: add code and image security scanning #477

Job	Run time
Codex Comments	32s
Detect changed paths	27s
Trivy filesystem scan	32s
Lint GitHub Actions	51s
Terraform (fmt/validate/tflint/trivy)	44s
test	-1s
lint	-1s
E2E (Kind + CNPG + Templates)	0s
Trivy image scan	-1s
Publish GHCR :main	-1s
	3m 2s

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