feat: implement validate API key check endpoint and GCS verification

[yiyche]

mainly added

• api router file: pipeline/workflow/ingestion-helper/routes/ingestion.py (POST /ingestion/start)
• api key validation: tests DC_API_KEY against https://api.datacommons.org/v2/node before job launch to fail fast on 401/403.
• aditional GCS artifact verification: ensure bucket + file combo exists
• check for already running ingestion jobs (comment on PR under DCP repo)

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

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0 new issues

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🟢 Metrics 50 complexity

Metric	Results
Complexity	50

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[gemini-code-assist]

Code Review

This pull request introduces a new ingestion router with /start and /config endpoints to validate, trigger, and inspect Cloud Run ingestion jobs. It also adds GCS bucket and file existence checks to the storage client, updates dependencies, and includes comprehensive unit tests. The review feedback focuses on improving robustness and error handling: guarding against potential AttributeErrors when auto-discovering job configurations, logging warnings for failed Cloud Run API requests, and updating error messages to account for permission issues during GCS bucket and file checks.