⚡ Optimize SynchronizedCollection.Get allocations

[johnstrand]

💡 What: Added caching to SynchronizedCollection.Get using an IReadOnlyList<T> snapshot that is updated only when the collection is mutated via Integrate().
🎯 Why: Previously, Get() called .ToList() unconditionally, causing an O(N) allocation on every single read operation, even if the collection had not changed.
📊 Measured Improvement: In a short run benchmark of 100 repeated gets on a 1000-element collection, allocations dropped from ~396 KB to 0 KB, and the time taken went from ~367 us to ~8.7 us (a massive speedup).

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PR created automatically by Jules for task 16063287763031452242 started by @johnstrand

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