chore(ecdsa): migrate to hardhat-verify and add Sepolia network support

This commit updates the hardhat verification tooling and adds support for
Sepolia testnet deployments:

Changes:
- Replace deprecated @nomiclabs/hardhat-etherscan with @nomicfoundation/hardhat-verify
- Add Sepolia external artifacts directory for dependency resolution
- Add allowlist weights configuration for Sepolia network
- Include RandomBeacon, T token, and TokenStaking contract artifacts for Sepolia
- Add deployment function IDs to all deploy scripts for better tracking
- Remove unused mainnet OpenZeppelin deployment metadata
- Update package dependencies and lockfiles

These changes enable deployment and testing on Sepolia while modernizing
the verification infrastructure to use the latest Hardhat tooling.

Author: lrsaturnino

solidity/ecdsa/.openzeppelin/mainnet.json

@@ -44,3 +44,4 @@ func.tags = ["EcdsaSortitionPool"]
 // TokenStaking and T deployments are expected to be resolved from
 // @threshold-network/solidity-contracts
 func.dependencies = ["TokenStaking", "T"]
+func.id = "deploy_ecdsa_sortition_pool"

solidity/ecdsa/deploy/01_deploy_ecdsa_sortition_pool.ts

@@ -30,3 +30,4 @@ export default func
 
 func.tags = ["EcdsaDkgValidator"]
 func.dependencies = ["EcdsaSortitionPool"]
+func.id = "deploy_ecdsa_dkg_validator"

solidity/ecdsa/deploy/02_deploy_dkg_validator.ts

@@ -5,6 +5,13 @@ const func: DeployFunction = async (hre: HardhatRuntimeEnvironment) => {
   const { getNamedAccounts, deployments, ethers, helpers } = hre
   const { deployer } = await getNamedAccounts()
 
+  // Skip if WalletRegistry already deployed (for existing testnet deployments)
+  const existingWalletRegistry = await deployments.getOrNull("WalletRegistry")
+  if (existingWalletRegistry) {
+    console.log(`using existing WalletRegistry at ${existingWalletRegistry.address}`)
+    return true
+  }
+
   const EcdsaSortitionPool = await deployments.get("EcdsaSortitionPool")
   const TokenStaking = await deployments.get("TokenStaking")
   const ReimbursementPool = await deployments.get("ReimbursementPool")
@@ -79,3 +86,4 @@ func.dependencies = [
   "TokenStaking",
   "EcdsaDkgValidator",
 ]
+func.id = "deploy_wallet_registry"

solidity/ecdsa/deploy/03_deploy_wallet_registry.ts

@@ -46,7 +46,10 @@ const func: DeployFunction = async (hre: HardhatRuntimeEnvironment) => {
 
   // Load pre-calculated weights from JSON
   // These weights include accumulated stakes from consolidated beta stakers
-  const weightsPath = path.join(__dirname, "data/allowlist-weights.json")
+  // Use network-specific file if available
+  const networkSpecificPath = path.join(__dirname, `data/allowlist-weights-${hre.network.name}.json`)
+  const defaultPath = path.join(__dirname, "data/allowlist-weights.json")
+  const weightsPath = fs.existsSync(networkSpecificPath) ? networkSpecificPath : defaultPath
 
   if (!fs.existsSync(weightsPath)) {
     throw new Error(
@@ -309,6 +312,7 @@ export default func
 
 func.tags = ["InitializeAllowlistWeights"]
 func.dependencies = ["Allowlist", "UpgradeWalletRegistryV2"]
+func.id = "initialize_allowlist_weights"
 
 // Only run this script when explicitly requested
 func.skip = async () => !process.env.MIGRATE_ALLOWLIST_WEIGHTS