Add gitleaks pre-commit hook for secret detection

[devin-ai-integration]

Summary

Adds gitleaks as a pre-commit hook to automatically detect secrets before they are committed to the repository.

Changes:

• .pre-commit-config.yaml — New pre-commit configuration using gitleaks v8.30.1
• .gitleaks.toml — Custom gitleaks config with an allowlist that excludes lock files (*.lock, package-lock.json) from scanning
• README.md — Appended setup instructions for installing and running the pre-commit hook

Review & Testing Checklist for Human

• Verify v8.30.1 is an acceptable gitleaks version for this project (latest stable at time of PR creation)
• Run pre-commit install && pre-commit run --all-files locally to confirm the hook works and does not flag false positives in existing code
• Review the .gitleaks.toml allowlist — confirm that excluding only lock files is sufficient, or add project-specific paths/rules as needed

Notes

• No functional code changes — config and documentation only
• Developers will need to run pip install pre-commit && pre-commit install once to activate the hook locally

Link to Devin session: https://partner-workshops.devinenterprise.com/sessions/cb042592bbee4434846b387a669ba5cb

[devin-ai-integration]

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