docs: rewrite top-level docs to match the post-cleanup reality #323

Job	Run time
SAST with Semgrep	53s
Go Dependency Vulnerability Scan (api)	18s
Secret Scanning with Gitleaks	7s
Go Dependency Vulnerability Scan (k8s-controller)	7s
npm Dependency Vulnerability Scan	55s
CodeQL Analysis (javascript)	1m 44s
Dockerfile Linting (api)	8s
Trivy Container Image Scan (api)	1m 28s
Dockerfile Linting (ui)	10s
Dependency Review	7s
CodeQL Analysis (go)	4m 54s
Dockerfile Linting (k8s-controller)	11s
Trivy Container Image Scan (ui)	42s
Kubernetes Manifest Security Scan	33s
Trivy Container Image Scan (kubernetes-controller)	20s
Security Scan Summary	4s
	12m 41s

Provide feedback