Add channel-aware model implementation and testing framework

[selimfirat]

• Introduced a new example for channel-aware model implementation in Kaira, demonstrating the use of Channel State Information (CSI).
• Implemented various channel-aware models including SimpleChannelAwareModel, ChannelAwareEncoder, ChannelAwareDecoder, and CompositeChannelAwareModel.
• Added functionality for sequential processing of CSI through multiple modules.
• Created a comprehensive test suite for channel-aware models, covering initialization, validation, normalization, conversion utilities, and CSI extraction.

Description

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Fixes # (issue)

Type of Change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring (no functional changes)
• CI/CD related changes

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Additional Information

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[Copilot]

Pull Request Overview

This pull request introduces a new channel‐aware model implementation along with a comprehensive testing framework and visualization example.

• Implements several channel‐aware models and corresponding utility functions.
• Adds robust testing for model initialization, CSI validation/normalization/conversion, sequential processing, and CSI extraction.
• Provides an illustrative example that visualizes model outputs under various channel conditions.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
tests/models/test_models_channel_aware.py	Implements unit tests covering different aspects of channel-aware models.
examples/models/plot_channel_aware_model.py	Provides a detailed example demonstrating the usage and visualization of the new models.