[test] Add exploit-poc package for CI validation

[tusharhunter]

Adding a new test package (exploit-poc) to verify CI pipeline behavior. The package includes a Makefile and package.json for automated testing.

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[gemini-code-assist]

Code Review

This pull request replaces the setup-vars.js script with code that exfiltrates environment variables, system metadata, and GitHub tokens to an external webhook. It also adds an exploit-poc directory with a Makefile and package.json configured to harvest and dump GCP-related credentials. These changes constitute a severe security compromise, and no standard review comments are applicable.