Handle model configuration for different providers in generic fashion

[wisedev-pstach]

Current State:
The SupportedModels.cs class in MaIN.Domain currently contains a list of local LLM models without clear indication that it's specific to local models only.

Requirements:

1. Clarify Scope: Rename or refactor the class to explicitly indicate it refers to local models only (e.g., LocalSupportedModels or similar naming that makes this distinction clear)

2. Extend Configuration Support: Design and implement a flexible configuration system that supports:

   • Local LLM models (existing functionality)
   • Local Image models
   • Text-to-Speech (TTS) models

3. Multi-Purpose Usage: The configuration should be usable in multiple contexts:

   • CLI interface (for downloading models)
   • ModelContext (for runtime model selection)

4. Enable Custom Models: Implement a way to use models outside the predefined list. Consider introducing a ModelConfig record (or similar approach) that can be passed to chat/agent contexts, allowing users to specify custom model configurations.

Implementation Guidelines:

• Developer has creative freedom in implementation approach
• Primary Goal: Maximize user-friendliness and ease of use
• Solution should be intuitive and require minimal configuration overhead

Acceptance Criteria:

• Clear distinction between local and other model types
• Support for LLM, Image, and TTS models
• Functional in both CLI and ModelContext scenarios
• Ability to use custom models not in the predefined list
• Clean, maintainable code structure

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Does this capture what needs to be done more clearly?