Enhance NEAR Smart Contracts with Sharding and Call Safety

NEAR Protocol’s Nightshade sharding splits blocks into chunks, enabling asynchronous cross-contract calls via a Promise system. Dynamic Resharding adjusts shard count dynamically. Cross-contract calls use attached gas of 5T and 2T units. Asynchronous callbacks risk race conditions. Mitigation includes #[private] callbacks, state locks, and rollback in StakingContract to prevent exploits like double staking and underflow errors.