Problem

• Transcription tests fail on import when faster_whisper is not installed
• test_stat_oserror fails on Python 3.14 because Path.exists()/Path.is_file() no longer delegate to Path.stat()
• test_update_gateway_restart fails on non-Linux platforms because is_linux() isn't mocked

Fix

• Inject a sys.modules stub for faster_whisper in both transcription test files
• Simplify test_stat_oserror to patch Path.stat directly and assert the validation function returns an error (no call_count threshold)
• Mock is_linux → True in the gateway restart test

Testing

• All three test files pass on macOS with Python 3.14