fix: resolve race condition in NetworkDataCache with proper LRU implementation

- Replace O(n) array-based LRU with O(1) Map-based LRU using insertion order
- Add stale-while-revalidate pattern for resilience during fetch failures
- Add proper disposal pattern with Symbol.asyncDispose support
- Extract magic numbers into named constants (CACHE_DEFAULTS)
- Add comprehensive metrics tracking (hits, misses, evictions, staleHits)
- Add ensureNotDisposed guard to prevent operations on disposed cache

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Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: DaMandal0rian