fix(audit): drop redundant leaf gap from NPM

Bailsec Issue_02 (Informational). NonfungiblePositionManager is the
leaf of its inheritance chain — nothing inherits from it — so a leaf
__gap reserves slots that no child contract's layout would otherwise
depend on. Per OZ convention, storage gaps belong on base contracts,
not leaves. Future state additions to NPM just append after
_tokenDescriptor regardless.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: razww

src/periphery/NonfungiblePositionManager.sol

@@ -73,8 +73,6 @@ contract NonfungiblePositionManager is
     /// @dev The address of the token descriptor contract, which handles generating token URIs for position tokens
     address private _tokenDescriptor;
 
-    uint256[45] private __gap;
-
     constructor(address _factory, address _WETH9) PeripheryImmutableState(_factory, _WETH9) {}
 
     function initialize(address _tokenDescriptor_) external initializer {