Fix method redefined warning for log_regexp_timeout= (Ruby 4.0+) (#721)

## What this does

On Ruby 4.0+, `require "ruby_llm"` emits:

    warning: method redefined; discarding old log_regexp_timeout=

The `option` class method generates a setter via `attr_accessor`, which
is then
overridden by the custom `log_regexp_timeout=` setter. This adds
`remove_method`
before the redefinition to suppress the warning. A regression spec is
included.

## Type of change

- [x] Bug fix
- [ ] New feature
- [ ] Breaking change
- [ ] Documentation
- [ ] Performance improvement

## Scope check

- [x] I read the [Contributing
Guide](https://github.com/crmne/ruby_llm/blob/main/CONTRIBUTING.md)
- [x] This aligns with RubyLLM's focus on **LLM communication**
- [x] This isn't application-specific logic that belongs in user code
- [x] This benefits most users, not just my specific use case

## Quality check

- [x] I ran `overcommit --install` and all hooks pass
- [x] I tested my changes thoroughly
  - [x] All tests pass: `bundle exec rspec`
- [ ] I updated documentation if needed
- [x] I didn't modify auto-generated files manually (`models.json`,
`aliases.json`)

## AI-generated code

- [x] I used AI tools to help write this code
- [x] I have reviewed and understand all generated code (required if
above is checked)

## API changes

- [x] No API changes

Co-authored-by: Carmine Paolino <carmine@paolino.me>

Author: dominion525

lib/ruby_llm/configuration.rb

@@ -81,6 +81,7 @@ def instance_variables
       super.reject { |ivar| ivar.to_s.match?(/(_id|_key|_secret|_token|_credential_provider)$/) }
     end
 
+    remove_method :log_regexp_timeout=
     def log_regexp_timeout=(value)
       if value && !Regexp.respond_to?(:timeout)
         RubyLLM.logger.warn("log_regexp_timeout is not supported on Ruby #{RUBY_VERSION}")

spec/ruby_llm/configuration_spec.rb

@@ -64,4 +64,11 @@
       )
     end
   end
+
+  describe 'method redefinition warnings' do
+    it 'does not emit method redefined warning for log_regexp_timeout=' do
+      warnings = `#{RbConfig.ruby} -W -e 'require "ruby_llm"' 2>&1`
+      expect(warnings).not_to include('method redefined')
+    end
+  end
 end