Fix: Add resolve method delegation from Models instance to class

[kieranklaassen]

Summary

• Adds missing resolve instance method that delegates to the class method
• Fixes usage of RubyLLM.models.resolve in the migration template
• Includes comprehensive test coverage with TDD approach

Context

The upgrade migration template at lib/generators/ruby_llm/upgrade_to_v1_7/templates/migration.rb.tt uses RubyLLM.models.resolve on lines 74 and 139. However, RubyLLM.models returns a Models instance, which didn't have the resolve method - it was only available as a class method.

Changes

• Added resolve instance method in Models class that delegates to self.class.resolve
• Added test coverage for all three usage patterns:
  • With provider specified
  • Without provider (auto-detection)
  • With assume_exists option for unknown models

Test plan

• Run bundle exec rspec spec/ruby_llm/models_spec.rb -e resolve - all tests pass
• Verified the migration template can now use RubyLLM.models.resolve without errors

🤖 Generated with Claude Code

[tpaulshippy]

Looks like this has some Layout/TrailingWhitespace offenses from rubocop. All 8 autocorrectable.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.29%. Comparing base (0d23da4) to head (89605e2).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #407      +/-   ##
==========================================
+ Coverage   84.27%   84.29%   +0.01%     
==========================================
  Files          36       36              
  Lines        1895     1897       +2     
  Branches      493      493              
==========================================
+ Hits         1597     1599       +2     
  Misses        298      298              

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