Add code review for config layer and registry implementation

[Copilot]

Provided comprehensive code review for the new configuration layer with registry pattern as requested by @Sulimankhail.

Review Summary

Identified 7 key issues across architecture, error handling, and code quality:

Critical:

• WildcardDict.__getitem__ returns list instead of single value, breaking standard dict interface expectations
• Python 3.9+ type hints (list[Hashable]) incompatible with pyproject.toml requirement of >=3.7

Important:

• Accelerator properties use print() instead of logging/exceptions for missing configurations
• Empty __str__ implementation should be completed or removed
• Large blocks of commented code in device.py need removal or uncommenting

Code quality:

• Missing docstrings on WildcardDict, Accelerator, and other public classes
• Minor formatting issue: missing space after # in comment

Strengths Noted

• Clean separation between config models and registry logic
• Type safety via Pydantic validation
• Extensible design with abstract base classes
• Intuitive Accelerator API for MML users
• Clever wildcard pattern matching for device lookup

The foundational design is solid but needs interface consistency and error handling improvements before merge.

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