feat: implement u256 agglayer asset scaling up procedure

[partylikeits1983]

Asset Conversion Procedure Overview

This PR adds the functionality for converting between asset amounts with various decimals for Agglayer bridging operations.

Note:
Resolves: #2011

The convert_to_u256_scaled procedure converts Miden amounts to Agglayer compatible u256 format for bridging to agglayer chains.

[Copilot]

Pull request overview

This PR implements asset conversion functionality for Agglayer bridging operations, specifically adding a procedure to convert Miden asset amounts to U256 format with decimal scaling. The implementation includes a MASM procedure for computing scaled U256 values and Rust utilities for testing and integration.

Key changes:

• Adds convert_to_u256_scaled MASM procedure to scale asset amounts by powers of 10 and convert to U256 format
• Implements helper utilities for converting between Felt and U256 byte representations
• Provides comprehensive test coverage with two test cases validating scaling operations

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
crates/miden-lib/asm/agglayer/account_components/asset_conversion.masm	Core MASM implementation with pow10 helper and convert_to_u256_scaled procedure for asset scaling
crates/miden-lib/src/agglayer/mod.rs	Module definition providing asset conversion library initialization and component creation
crates/miden-lib/src/agglayer/utils.rs	Utility functions for converting between Felt values and U256 byte representations
crates/miden-testing/tests/agglayer/asset_conversion.rs	Test suite validating asset conversion with ETH and large amount scenarios
crates/miden-testing/tests/agglayer/mod.rs	Module declaration for agglayer tests
crates/miden-testing/tests/lib.rs	Adds agglayer test module to test suite
crates/miden-lib/src/lib.rs	Exposes agglayer module for testing/test features
crates/miden-lib/build.rs	Extends build script to compile agglayer account components
crates/miden-testing/Cargo.toml	Adds primitive-types dependency for U256 support in tests
Cargo.toml	Adds primitive-types to workspace dependencies
Cargo.lock	Locks new dependencies (primitive-types, byteorder, fixed-hash, hex, uint, static_assertions)

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[Copilot]

Pull request overview

Copilot reviewed 11 out of 12 changed files in this pull request and generated 4 comments.

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[partylikeits1983]

Renamed this PR to "feat: implement u256 agglayer asset scaling up procedure" since I think we should implement scaling down in a separate PR.

[partylikeits1983]

Importing U256 type.

[bobbinth]

Looks good! Thank you! I left a few comments inline - the main one is about using u64 multiplication to make the procedure much more efficient.

[bobbinth]

Looks good! Thank you! I left a few more comments inline.

[partylikeits1983]

Changed felts_to_u256_bytes return type from Vec<u8> to [u8; 32] and updated it to accept little-endian input order. Updated asset_conversion.masm to output U256 results in little-endian format and fixed stack comments to properly document intermediate values. Updated corresponding tests to match the new little-endian behavior across both Rust and MASM.

I think this is ready to merge @bobbinth @mmagician

[bobbinth]

All looks good! Thank you!