🧪 Add tests to verify App component routing

[artosien]

🎯 What: The missing test coverage for App routing logic was addressed.
📊 Coverage: Test coverage includes the default path (/), all specific sub-routes (/home, /capture, /stitching, /viewer/:id), and the default fallback/unknown route redirecting to Splash.
✨ Result: Enhanced test coverage that reliably verifies routing navigation changes rendering expected components, and added the foundational Vitest configuration with jsdom for future component tests.

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PR created automatically by Jules for task 13021331489849999863 started by @artosien

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