⚡ Bolt: Optimize GetRackCount to use O(1) network map lookup

[mleem97]

💡 What: Replacing FindObjectsOfType<Rack>() with NetworkMap.instance.GetNumberOfDevices()[2].
🎯 Why: FindObjectsOfType is O(N) and blocks the main thread, causing spikes in large facilities. The network map tracks this count natively in O(1) time.
📊 Impact: Transforms an O(N) scene-wide search into an O(1) array lookup, significantly improving API performance for external mods calling this method.
🔬 Measurement: Observe CPU frame timings via Unity Profiler when mods poll GetRackCount() frequently in a large data center scenario.

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PR created automatically by Jules for task 2505259594815862671 started by @mleem97

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