Add focus motor contract and integrate z-lock

[7jameslondon]

Summary

• introduce a FocusMotorBase capability with shared focus status IPC commands and propagate focus motor availability through MagScope
• update the simulated focus motor example and Z-LUT UI panel to use the new focus motor API and validate ranges
• implement Z-lock motion using focus motor status, clamping moves within motor limits and warning when no motor is present

Testing

• python -m pytest tests/test_process_manager.py tests/test_scope.py

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Codex Task