docs(onboarding): define approval lifecycle #10

Job	Run time
CodeQL (TypeScript/React)	1m 37s
Dependency Vulnerability Review	5s
CodeQL (.NET Backend)	37s
Hardcoded Secrets Detection	2s
NuGet Vulnerability Audit	0s
Tenant Isolation Security Tests	0s
Docker Image Security Scan	0s
npm Vulnerability Audit	0s
Security Scan Report	4s
Security Gate	3s
	2m 28s

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