fix: change tool_calls from dict to list

[akihikokuroda]

Pull Request

Issue

Fixes #1431

Description

This changed tool_calls from dict to list instead of set because of the follow reason

Aspect	Dict	Set	List
Parallel same-name calls	❌ Collapses	✓ Preserved	✓ Preserved
Execution order	✓ Preserved	❌ Lost	✓ Preserved
Duplicate handling	Overwrites silently	Deduplicates silently	Must validate explicitly
Component prefixing	✓ Works	❌ Order lost	✓ Works
Requires __hash__/__eq__	No	Yes	No
Equality semantics	N/A	Unclear	N/A
Observability	✓ Simple	❌ Hidden deduplication	✓ Visible duplicates
Implementation effort	N/A	Medium (add hash/eq)	Low (validate helper)

Testing

• Tests added to the respective file if code was changed
• New code has 100% coverage if code was added
• Ensure existing tests and github automation passes (a maintainer will kick off the github automation when the rest of the PR is populated)

Attribution

• AI coding assistants used

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Adding a new component, requirement, sampling strategy, or tool?

If your PR adds or modifies one of the types below, check the matching box. A checklist of type-specific review items will be posted as a comment.

• Component
• Requirement
• Sampling Strategy
• Tool

NOTE: Please ensure you have an issue that has been acknowledged by a core contributor and routed you to open a pull request against this repository. Otherwise, please open an issue before continuing with this pull request.

[akihikokuroda]

This has broader changes than expected.