refactor(theme): remove light theme and enforce dark mode across all apps

tests/contracts/MockGroth16Verifier.sol

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+contract MockGroth16Verifier {
+    function verifyProof(bytes memory) external pure returns (bool) {
+        return true;
+    }
+}