Aggregate hot keys across cluster nodes

[ravjotbrar]

Description

Hot keys fan-out & aggregation

• Hot key requests are fanned out to all nodes in clusterNodesRegistry when a clusterId is present
• Results are aggregated by summing access counts per key, with size and TTL preserved from the first node that has them
• Hot keys state is keyed by clusterId for cluster connections

Error handling

• A yellow warning banner is shown when partial data is returned alongside node errors
• Node-level errors are collected per node and returned alongside data in hotKeysFulfilled rather than firing individual hotKeysError messages
• If all nodes fail or monitor isn't running, a fulfilled response with empty data is still sent so the UI displays the new banner

Hot key calculation fix

• calculateHotKeysFromMonitor previously counted every command argument as a key. It now only counts args[0] for single-key commands, all args for mget/json.mget, and every other arg for mset

Cluster topology fix

• Added refreshAllClusterRegistriesLoop to periodically broadcast updated cluster topology to all connected clients
• Simplified reconcileClusterMetricsServers — removed getInitialClient indirection, increased reconcile interval to 10s

Misc

• Renamed clusterNodesMap → connectedNodesByCluster throughout for clarity
• Added clusterNodesRegistry to the Deps type so all action handlers have access to the full cluster node map

Change Visualization

Include a screenshot/video of before and after the change.