Updated the `IContractApplication` interface:
- Added `PrintOneAsync(long id)` and `PrintAllAsync(List<long> ids)` methods.
- Corrected formatting of `DeleteAllContarcts(List<long> ids)`.
- Grouped changes under the `NewChangeByHeydari` region.
Introduced the `ContractPrintViewModel` class (currently empty).
Implemented `PrintOneAsync` and `PrintAllAsync` in `ContractApplication` with `NotImplementedException`.
These changes prepare the codebase for contract printing functionality.