Adds optional huggingface_id field to model configurations for linking open-weight models

[bbartels]

Fixes: #941
Adds optional huggingface_id field to model configurations for linking open-weight models to their HuggingFace repositories (e.g., MiniMaxAI/MiniMax-M2.5).

Changes

• Schema: Added huggingface_id string field with format validation (org/model-name) and constraint requiring open_weights=true
• Web UI: New sortable column with clickable links to https://huggingface.co/{id}
• Documentation: Updated README model configuration example

Example

name = "MiniMax M2.5 TEE"
open_weights = true
huggingface_id = "MiniMaxAI/MiniMax-M2.5"  # Optional, links to HuggingFace repo

The field appears in the web interface as a link when present, displays "-" otherwise.

[bbartels]

In a separate PR, i'll populate this data across providers