⚡ Bolt: Use Promise.all for federation stats fetch

[spupuz]

💡 What: Refactored the sequential for...of loop in FederationSummaryWidget.jsx to use concurrent network requests via Promise.all.
🎯 Why: Using await fetch in a sequence creates an O(N) bottleneck, delaying the rendering of the multi-site overview as the number of federated nodes increases.
📊 Impact: Reduces network latency significantly; requests to all federated nodes are now dispatched in parallel. Load time is bounded by the slowest node.
🔬 Measurement: Test with multiple federated nodes and observe the load time of the FederationSummaryWidget in the browser dev tools network tab.

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PR created automatically by Jules for task 3048617062845617885 started by @spupuz

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[spupuz]

Closing as duplicate. This intent (concurrent fetching for FederationSummaryWidget) was already merged in PR #399.