🧪 [testing improvement] Added unit tests for wpAPI.fetchContent

[google-labs-jules]

🎯 What: The testing gap for fetchContent API wrapper was addressed.
📊 Coverage: The test cases now cover calling behavior for loading table visibility, default parameter values, custom queries (full parameter), and error handling exceptions.
✨ Result: Improved test coverage on client side interactions logic, ensuring URL construction functions identically after future refactoring.

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PR created automatically by Jules for task 1025621481160493481 started by @instituto-ops

[google-labs-jules]

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