RubyLLM::Modalities.new possible being used in RubyLLM::Models first.

[Eric-Guo]

When I working on #168, I found if using below

chat = RubyLLM.chat(
  model: 'dify-api', # Your custom deployment name
  provider: :dify,                # MUST specify provider
  assume_model_exists: true         # Bypass registry check
)

I will got

/Users/guochunzhong/git/oss/ruby_llm/lib/ruby_llm/models.rb:60:in 'RubyLLM::Models.resolve': uninitialized constant RubyLLM::Modalities (NameError)

                             RubyLLM::Modalities.new({ input: %w[text image], output: %w[text] }),
                                    ^^^^^^^^^^^^
Did you mean?  RubyLLM::Models
	from /Users/guochunzhong/git/oss/ruby_llm/lib/ruby_llm/chat.rb:64:in 'RubyLLM::Chat#with_model'
	from /Users/guochunzhong/git/oss/ruby_llm/lib/ruby_llm/chat.rb:23:in 'RubyLLM::Chat#initialize'
	from /Users/guochunzhong/git/oss/ruby_llm/lib/ruby_llm.rb:42:in 'Class#new'
	from /Users/guochunzhong/git/oss/ruby_llm/lib/ruby_llm.rb:42:in 'RubyLLM.chat'
	from (irb):1:in '<main>'
	from <internal:kernel>:168:in 'Kernel#loop'
	from bin/console:23:in '<main>'

Which RubyLLM::Modalities.new({ input: %w[text image], output: %w[text] }) used before class ModelInfo used.

So I guess it should be move out from original place.