[ayushdoesdev]

Closes #1

Summary

• Resolve requirements files against the repository root before parsing.
• Reject include paths (including symlink targets) that escape the checkout.
• Track visited requirements files so cyclic -r / --requirement references terminate and repeated includes are not parsed repeatedly.
• Add regression coverage for nested/repeated includes, cycles, parent-directory traversal, and symlink escapes.

Validation

• Verified the updated scanner and regression test files are present on this branch.
• I could not execute the Python test suite in this environment. The repository CI should run the configured scanner tests when this PR is opened.

This is a focused backend scanner safety/correctness fix; no frontend or landing-page files are changed.