fix: lazy-import fcntl to prevent crash on Windows

[kouyouqi123]

Fixes #166

Problem

linux.py has import fcntl at module level. On Windows, fcntl is not available (Unix-only), so importing trcc.adapters.system (which side-effect imports all OS modules) crashes with ModuleNotFoundError: No module named 'fcntl'.

Fix

Moved import fcntl from module level to inside the methods that use it, so it's only imported on Linux where those methods are actually called.

[Lexonight1]

Thank you for catching this and taking the time to send a fix — much appreciated. Good news: it's already resolved in main and shipped in v9.7.1 — fcntl is now imported lazily inside the SCSI ioctl methods in linux.py, so the Linux module imports cleanly on Windows (landed while fixing #166). I'll close this as already-fixed, but thank you for diagnosing it and helping out. 🙏

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