Update @nomicfoundation/hardhat-toolbox to latest version (6.1.0) and fix compatibility issues

[Copilot]

This PR updates the project's devDependencies to use the latest version of @nomicfoundation/hardhat-toolbox (6.1.0) and resolves all compatibility issues that arose from the update.

Changes Made

1. Updated Hardhat Toolbox

• Updated @nomicfoundation/hardhat-toolbox from ^6.1.0 to the latest version
• Removed redundant individual dependencies (@nomicfoundation/hardhat-ethers, @nomicfoundation/hardhat-chai-matchers, chai, ethers) that are now provided by the toolbox
• Updated hardhat to ^2.26.3 for compatibility with the toolbox

2. Fixed Configuration

• Updated hardhat.config.js to import @nomicfoundation/hardhat-toolbox instead of individual @nomicfoundation/hardhat-ethers
• This provides access to all toolbox features including ethers, chai matchers, network helpers, verification tools, gas reporting, and coverage

3. Resolved OpenZeppelin Contracts Compatibility

Fixed constructor issues in smart contracts due to OpenZeppelin Contracts v5.x requiring explicit owner parameters:

SEQICO.sol:

// Before
constructor(...) {

// After  
constructor(...) Ownable(msg.sender) {

SEQToken.sol:

// Before
constructor(...) ERC20("SEQ Token", "SEQ") {
    // ...
    _transferOwnership(owner);
}

// After
constructor(...) ERC20("SEQ Token", "SEQ") Ownable(owner) {
    // ... (removed manual ownership transfer)
}

4. Fixed ES Module Imports

Updated all script files to use compatible import syntax:

// Before
import { ethers } from "hardhat";

// After
import hre from "hardhat";
const { ethers } = hre;

This resolves ES module compatibility issues while maintaining the same functionality.

Verification

All existing functionality has been tested and verified:

• ✅ Contract compilation successful
• ✅ Both deployment scripts (deploy.js and deploy-DE.js) working correctly
• ✅ All tests passing with gas reporting
• ✅ Example calculation scripts (example-values.js, price-examples.js) functioning
• ✅ GitHub Actions workflow compatibility maintained

Benefits

1. Latest Features: Access to the newest Hardhat toolbox features and improvements
2. Simplified Dependencies: Reduced dependency management by using the comprehensive toolbox
3. Better Maintenance: Single package to update instead of multiple individual dependencies
4. Enhanced Testing: Improved testing capabilities with the latest toolbox features

The update ensures the project uses the most current and stable versions of the Hardhat ecosystem while maintaining full backward compatibility with existing contracts and scripts.

This pull request was created as a result of the following prompt from Copilot chat.

Update the project's devDependencies to use the latest version of @nomicfoundation/hardhat-toolbox. Run 'npm install @nomicfoundation/hardhat-toolbox@latest --save-dev' to update package.json and package-lock.json accordingly. Ensure all workflow and contract scripts continue to function with the new toolbox version.

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