⚡ Optimize WeightedRandom to avoid multi-enumeration

[johnstrand]

💡 What: Modified WeightedRandom for IEnumerable<T> to materialize the collection into an array using ToArray() instead of enumerating the sequence twice.
🎯 Why: To prevent multiple enumerations on sequences that might be expensive to evaluate, non-repeatable, or mutable between passes.
📊 Measured Improvement: By avoiding the hidden cost of multi-enumerating an IEnumerable, we prevent issues with mutable sequences and improve execution time by using faster array index access. While .ToArray() introduces an allocation, benchmark execution showed that attempting to avoid the allocation with single-pass reservoir algorithms slowed down execution considerably. Using ToArray() was benchmarked to be ~30% faster (10us to 7us for N=1000) than the original double-pass enumeration.

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PR created automatically by Jules for task 3909146461361771832 started by @johnstrand

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