feat(sdk/dotnet): implement .NET SDK packages (Contracts, Authorizati… #3

Job	Run time
CodeQL (.NET Backend)	33s
Hardcoded Secrets Detection	3s
CodeQL (TypeScript/React)	1m 30s
Dependency Vulnerability Review	5s
npm Vulnerability Audit	0s
Tenant Isolation Security Tests	0s
NuGet Vulnerability Audit	0s
Docker Image Security Scan	0s
Security Gate	2s
Security Scan Report	3s
	2m 16s

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