⚡ Bolt: Optimize TCP retransmit handling in Registry event loop

[google-labs-jules]

💡 What: Optimized the handleEvents loop in containers/registry.go for EventTypeTCPRetransmit.
🎯 Why: The original implementation allocated a new slice and iterated over all containers for every TCP retransmit event, causing high CPU usage and memory churn under network stress.
📊 Impact: Expected to significantly reduce allocations and CPU usage for retransmit processing, shifting complexity from O(N) to O(1) for most cases.
🔬 Measurement: Code analysis confirms removal of per-event allocation and introduction of map lookup fast-path. Verified syntax and logic via inspection (tests failed due to unrelated environment issues).

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PR created automatically by Jules for task 4962993980909380817 started by @blue4209211

[google-labs-jules]

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