🧪 Add robust testing for format_date utility

[Jandir]

🎯 What: The format_date function in utils.py (which sanitizes dates from YouTube/Vimeo into YYYY-MM-DD formats) was previously untested, leaving a coverage gap for edge cases and unexpected inputs.

📊 Coverage: A new test file tests/test_utils.py was introduced. It uses pytest.mark.parametrize to rigorously cover:

• YouTube 8-digit numeric formats (both as string and int).
• Standard ISO formats (already correct dates).
• Empty, whitespace, or None inputs gracefully defaulting to "Desconhecida".
• Textual fallback rejection like "N/A" and "None" strings.
• Graceful passthrough for unexpected string formats.

✨ Result: Enhanced codebase reliability by ensuring the date extraction step behaves predictably without raising exceptions, preventing potential formatting regressions during future refactors. Test suite successfully validates 14 scenarios for the target logic.

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PR created automatically by Jules for task 17078472301702031387 started by @Jandir

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