Add Hugging Face model ecosystem support

[AgentGoose32]

Summary

• add a Hugging Face model ecosystem adapter backed by the Hugging Face models API
• support model URLs, revision URLs, config download URLs, huggingface-cli download install commands, model lists, recently updated models, package metadata, SHA-based versions, and namespaced purls
• seed huggingface.co as the default Hugging Face registry
• add model coverage for URLs, purl, model lists, metadata, downloads, licenses, siblings, and versions

Refs #1232

Validation

• ruby -c app/models/ecosystem/huggingface.rb
• ruby -c test/models/ecosystem/huggingface_test.rb
• ruby -c db/seeds.rb
• git diff --check

Full Rails test execution is blocked locally because this repo lockfile requires Bundler 4.0.10 while the system Ruby/Bundler cannot satisfy it.