fix: dedupe IStakeManager.deposit after master merge

The branch's IStakeManager (and its mock) add deposit() that new master also
declares — on the old base there was no clash, but rebased onto current master
the two collide into a duplicate function definition that fails to compile.
Remove the redundant declaration; a single deposit()/instantWithdraw() remains.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: razww

src/provider/interfaces/IStakeManager.sol

@@ -9,9 +9,6 @@ interface IStakeManager {
 
   function convertSnBnbToBnb(uint256 _amountInSlisBnb) external view returns (uint256);
 
-  /// @notice Stake native BNB and mint slisBNB to the caller.
-  function deposit() external payable;
-
   /// @notice Instantly redeem slisBNB for native BNB (no unbonding cooldown), minus an
   ///         instant-withdraw fee. The caller must approve `_amountInSlisBnb` to this contract.
   /// @return bnbAmount The native BNB sent to the caller.

test/moolah/mocks/MockStakeManager.sol

@@ -20,8 +20,6 @@ contract MockStakeManager is IStakeManager {
     return (_amountInSlisBnb * 1e18) / exchangeRate;
   }
 
-  function deposit() external payable {}
-
   function instantWithdraw(uint256) external pure returns (uint256) {
     return 0;
   }