⚡ Bolt: Optimize Zustand record filtering in stores

[georgi]

This PR implements a performance optimization focused on reducing intermediate array allocations in critical Zustand stores (ErrorStore, ExecutionTimeStore, VibeCodingStore).

What:
Replaced Object.fromEntries(Object.entries(record).filter(...)) patterns with optimized for...in loops and shallow-copy-and-delete operations.

Why:
The previous pattern allocates intermediate arrays during Object.entries() which negatively impacts garbage collection and overall main thread execution time, particularly during rapid dictionary updates and workflow resets.

Impact:
Improves execution and cleanup responsiveness during store operations.

Also updated ZUSTAND_BEST_PRACTICES.md so that future developers will adhere to this more performant pattern. Tests and linters passing.

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PR created automatically by Jules for task 8479677575715052144 started by @georgi

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