Implement UCEF version of the xERC20 token

[gabspeck]

This adds a UCEF version of the xERC20 token, AKA ERC-7281.

The lockbox and factory contracts were not ported since they are not relevant to our goals with SIlent Data at this moment.

Drive-by changes:

• Change the version of the Silent Data dependencies to their current public ones
• Add the ability to select the "create2" strategy when deploying Ignition modules from the deploy:module script and define the salt used in an environment variable, to allow for repeatable contract addresses across chains.
• Change the _authorizeBalance declaration in the abstract UCEF.sol to not contain a function body and force inheriting contracts to implement it.
• Create Hardhat tasks:
  • call: issue eth_call requests through Hardhat, making it possible to issue authenticated SD calls from the command line
  • xerc20:set-limits: send a transaction to set minting/burning limits on an XERC20 token

[Copilot]

Pull Request Overview

This PR implements a UCEF-compatible version of the xERC20 token standard (ERC-7281), which enables cross-chain token bridging with rate-limited minting and burning capabilities. The implementation allows bridges to mint and burn tokens within configurable limits that refill over time, while supporting a lockbox mechanism for unlimited operations.

Key changes:

• Adds XUCEF contract combining UCEF privacy features with xERC20 bridging mechanics
• Implements rate-limited minting/burning with linear limit replenishment over 24 hours
• Adds support for CREATE2 deployment strategy with configurable salt for deterministic cross-chain addresses

Reviewed Changes

Copilot reviewed 9 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
contracts/token/XUCEF.sol	Core xERC20 implementation with UCEF privacy extensions and bridge limit management
contracts/token/UCEF.sol	Changes _authorizeBalance to abstract method requiring implementation by inheriting contracts
test/token/XUCEF.test.ts	Comprehensive test suite covering deployment, limits, minting, burning, permits, and UCEF privacy behavior
ignition/modules/XUCEF.ts	Hardhat Ignition deployment module for XUCEF token
ignition/parameters/XUCEF.json.example	Example configuration parameters for XUCEF deployment
package.json	Updates dependencies and adds xerc20 library; modifies deploy:module script to support CREATE2 strategy
hardhat.config.ts	Adds Ignition configuration for CREATE2 deployment with environment-based salt
pnpm-workspace.yaml	Configures native dependencies for workspace
.env.example	Adds CREATE2_SALT environment variable

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

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