Summary

• Replace the malformed GitHub API curl request with the public raw.githubusercontent.com pinned source URL
• Remove the unnecessary GH_TOKEN dependency from the fetch step
• Add regression coverage scoped to the pinned source fetch step

Test Plan

• python3 -m unittest tests.test_scripts.ScriptTests.test_ci_workflow_validates_against_pinned_source -v
• python3 -m unittest discover -s tests -v
• python3 -m py_compile target scripts/tests and sh -n wrapper scripts
• Extracted and executed the CI fetch run block; fetched pinned FABLE-5 source successfully