When a DNS lookup fails, the code used the expired cache but did not update its lifetime
This caused the system to get stuck always tryng the same incorrect address

Now, when we fall back to an expired cache due to an error, we renew its lifetime
This prevents repeated attempts with the same broken address and gives time for the DNS to recover

Improves system stability in DNS failure scenarios

- Implement lazy cleanup with 30-second throttling to remove expired entries
- Add MAX_CACHE_SIZE limit of 1000 entries with automatic pruning
- Clean up cache without background timers to allow clean process exit
- Add comprehensive tests for cache management functionality

…il addresses

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>