[spelech]

Summary

• Add IsWindowVisible and ReleaseTransientBuffers() on MainViewModel to pause 5-second background polling and release large image byte arrays when the window is hidden to the system tray.
• Throttle Ollama.LoadInstalledModelsAsync during background polling so it only runs when InstalledModels is empty or every 12th tick (~60s), while preserving immediate model loading on explicit RefreshStatusAsync() calls.
• Skip clearing and rebuilding InstalledModels in OllamaLibraryViewModel.LoadInstalledModelsAsync when the returned models match existing items, and suppress per-item ApplyFilter() invocations during batch updates.
• Return early in UpdateHardwareTelemetry across OllamaLibraryViewModel, HuggingFaceSearchViewModel, and CivitaiSearchViewModel when VRAM and RAM values are unchanged.
• Dispose transient HttpHelper.CreateClient(ApiBase) instances with using var client across Ollama, HuggingFace, and Civitai ViewModels.
• Update MainWindow.OnClosing and App.ShowMainWindow to manage IsWindowVisible, release transient image buffers on hide, and trigger a status refresh on restore.
• Add unit tests in OllamaLibraryViewModelTests and MainViewModelTests.