⚡ Bolt: [performance improvement] Memoize list items in ProgressPanel and LogPanel

[primoscope]

💡 What: Extracted DownloadItem and LogItem inner .map() closures into their own React.memo components in ProgressPanel.tsx and LogPanel.tsx. Also moved helper functions (formatSpeed, formatETA, getStatusColor, getLogColor) outside of the main component scope so they are not recreated on every render. Log messages now generate an explicit id when received, replacing array indices as the component key to ensure stability during filtering or truncation.
🎯 Why: Component lists populated by fast-updating WebSocket streams (like progress updates or chatty logs) cause the entire parent component to re-render. Since the WebSocket sends new object references, React forces a full reconciliation of the entire list, even for elements that haven't changed.
📊 Impact: Expected to significantly reduce React reconcile cycles and DOM manipulation on the frontend, resulting in lower CPU usage and a smoother interface, particularly when there are dozens of active downloads or hundreds of logs. Only the specific download that receives a progress update will re-render.
🔬 Measurement: Verify by starting multiple downloads or producing many logs while observing the React Profiler. You will see that previously unchanged items would re-render continuously, and now they will skip re-rendering.

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PR created automatically by Jules for task 1929547609096872959 started by @dzp5103

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