Add import information skill

[rohitkumarbhagat]

Summary

• add the read-only dc-import-info skill for inspecting Data Commons extract-and-transform imports
• provide bounded recipes for repository discovery, Scheduler configuration, Spanner status, GCS artifacts, Batch jobs, tasks, logs, and source provenance
• add centralized environment configuration, dependency readiness checks, and Python helpers for import discovery and finalized summaries
• register the skill and integrate its dependencies and tests with the repository test runner
• keep loader investigation, root-cause diagnosis, remediation, and cloud mutations explicitly out of scope

Testing

• .env/bin/python -m unittest discover -v -s agents/common -p "*_test.py"

[gemini-code-assist]

Code Review

This pull request introduces a read-only agent support framework (dc-import-info skill) for inspecting Data Commons import extraction and transformation (ET) pipelines. It adds structured operational recipes (GCP Batch, GCS, Logging, Scheduler, Spanner, and local), architectural references, environment configuration defaults, and Python helper scripts with unit tests. Feedback on the changes suggests defensively stripping whitespace from absolute_import_name in the GCS summary-list helper to prevent validation failures, and adding a conditional check in the Scheduler describe-job recipe's jq command to robustly handle missing or null HTTP target bodies.