🧪 Add integration test for ocr_endpoint exception handling

[chottokun]

🎯 What
We identified a missing error path test for the synchronous ocr_endpoint (/v1/ocr) exception handling. We addressed this by implementing test_ocr_endpoint_internal_error_integration in tests/test_api_errors.py.

📊 Coverage
The new test dynamically generates a valid, small dummy image and mocks app.state.engine.ocr to raise an Exception("Simulated engine failure"). It then calls the synchronous /v1/ocr endpoint using TestClient(app) and verifies:

• The endpoint correctly catches the exception.
• Returns an HTTP status code 500.
• The detail in the response matches "An internal error occurred during OCR processing".

✨ Result
Increased test coverage for critical error-handling paths of the synchronous API endpoint, preventing regressions and safeguarding against unexpected exception leakage.

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PR created automatically by Jules for task 17060343951938357982 started by @chottokun

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