feat(libraries): add fixed-point and low-level math primitives

src/libraries/UnsafeMath.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.36;
+
+/// @title Rounding-up integer division that trusts its non-zero denominator.
+library UnsafeMath {
+    function divRoundingUp(uint256 x, uint256 y) internal pure returns (uint256 z) {
+        assembly {
+            z := add(div(x, y), gt(mod(x, y), 0))
+        }
+    }
+}