feat: new MelleaTool class and adoption across mellea

[HendrikStrobelt]

Tool PR

Use this template when adding or modifying components in mellea/stdlib/tools/.

Description

• Link to Issue:

Implementation Checklist

Protocol Compliance

• Ensure compatibility with existing backends and providers
  • For most tools being added as functions, this means that calling convert_function_to_tool works

Integration

• Tool exported in mellea/stdlib/tools/__init__.py or, if you are adding a library of components, from your sub-module

Testing

• Tests added to tests/stdlib/tools/
• New code has 100% coverage
• Ensure existing tests and github automation passes (a maintainer will kick off the github automation when the rest of the PR is populated)

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• title ~= ^(fix|feat|docs|style|refactor|perf|test|build|ci|chore|revert|release)(?:\(.+\))?: