🧪 Add test coverage for scan_content logic in secret_scanner.py

[google-labs-jules]

🎯 What: The testing gap addressed was that the scan_content function in hooks/secret_scanner.py lacked testing for its main logic, including regex rule matching and exclusion logic handling.

📊 Coverage: The tests now thoroughly cover:

• Happy Path (no match): Verifying normal text correctly passes with no matched rule.
• Direct rule match (no exclusion): Verifying specific rules (like AWS keys) fire and trigger a block.
• Rule match triggering warnings: Verifying specific rules (like API keys) fire and trigger a warning, not a block.
• Exclusion context rule validation: Verifying exclusion regex correctly ignores instances containing test within their match context.
• Multiple rule matching: Verifying that encountering an excluded rule doesn't halt the process and properly captures subsequent real matches.

✨ Result: Test coverage for this hook file is robustly improved, guaranteeing refactoring safety.

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PR created automatically by Jules for task 14803250987321347641 started by @zknpr

[google-labs-jules]

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