🧪 Add missing unit test for L1CO code generation

[shuwang1]

🎯 What: Added a missing unit test testL1CO_PRN1 in GNSSCodesTests.swift to verify the correct generation of L1CO codes.
📊 Coverage: Tests the generate(prn: 1, type: .L1CO) function, ensuring it correctly returns the expected chip count of 1800.
✨ Result: Improved test coverage by explicitly validating the .L1CO case in the switch statement inside GNSSCodes.generate, matching the pattern of other tests.

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PR created automatically by Jules for task 6667302109775099869 started by @shuwang1

[google-labs-jules]

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