Support multiple contract calls

[yrong]

Context

It is a common pattern to compose multiple contract calls that execute sequentially and atomically. This PR introduces a separate command type and enhances AgentExecutor to support this behavior. The legacy single-contract call is retained solely for backward compatibility.

In addition, this PR further hardens the L1 adapter based on the new execution model. It also makes it easier to compose the two-step L2 transfer into a single atomic call:

• The agent approves the L1 adapter to use the asset.

• The agent then calls the L1 adapter, which pulls the asset and uses it to deposit into Across’s SpokePool contract.

Todo

A companion PR in the Polkadot SDK is still required.

[codecov]

Codecov Report

❌ Patch coverage is 63.88889% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.12%. Comparing base (d41cfe9) to head (71cbe16).

Files with missing lines	Patch %	Lines
...ntracts/src/l2-integration/SnowbridgeL1Adaptor.sol	0.00%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1676      +/-   ##
==========================================
+ Coverage   82.00%   82.12%   +0.12%     
==========================================
  Files          22       22              
  Lines        1006     1024      +18     
  Branches      190      197       +7     
==========================================
+ Hits          825      841      +16     
- Misses        164      166       +2     
  Partials       17       17              

Flag	Coverage Δ
solidity	82.12% <63.88%> (+0.12%)	⬆️

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[Copilot]

Pull request overview

This PR adds support for executing multiple contract calls atomically within a single command. A new CallContracts command type is introduced that complements the existing CallContract functionality, allowing agents to execute a sequence of external contract calls that will all revert if any individual call fails.

Changes:

• Added CallContracts command kind to execute multiple contract calls atomically
• Modified AgentExecutor.callContract signature to accept CallContractParams struct instead of individual parameters
• Updated SnowbridgeL1Adaptor to pull tokens from caller via safeTransferFrom instead of relying on pre-funding

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
contracts/test/mocks/HelloWorld.sol	Added consumeToken function to test ERC20 token transfers in multi-call scenarios
contracts/test/GatewayV2.t.sol	Added comprehensive tests for CallContracts including success and atomicity-on-failure scenarios
contracts/src/v2/Types.sol	Added CallContracts constant to CommandKind library
contracts/src/v2/Handlers.sol	Refactored callContract handler and added new callContracts handler
contracts/src/l2-integration/SnowbridgeL1Adaptor.sol	Changed from pre-funding model to pull-based token transfers with refund logic
contracts/src/Gateway.sol	Added v2_handleCallContracts handler and dispatch logic, plus minor formatting improvements
contracts/src/AgentExecutor.sol	Refactored callContract to accept struct parameter and added callContracts loop implementation

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[Copilot]

Extra blank line should be removed for consistency with the rest of the codebase.