Reject models from Parsera that does not have :provider or :id

[K4sku]

What this does

This PR filters out models from Parsera that have nil values for :provider or :id.
This prevents crashes on refreshing models which makes the cited statement from the site valid:

This method is safe to call from Rails applications, background jobs, or any running Ruby process.

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation
• Performance improvement

Scope check

• I read the Contributing Guide
• This aligns with RubyLLM's focus on LLM communication
• This isn't application-specific logic that belongs in user code
• This benefits most users, not just my specific use case

Quality check

• I ran overcommit --install and all hooks pass
• I tested my changes thoroughly
• I updated documentation if needed
• I didn't modify auto-generated files manually (models.json, aliases.json)

API changes

• Breaking change
• New public methods/classes
• Changed method signatures
• No API changes

Related issues

Fixes #270

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.72%. Comparing base (0f60067) to head (0c9507c).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #271   +/-   ##
=======================================
  Coverage   89.71%   89.72%           
=======================================
  Files          75       75           
  Lines        2811     2812    +1     
  Branches      555      555           
=======================================
+ Hits         2522     2523    +1     
  Misses        289      289           

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