Forward choice: and calls: from Agent tools macro to with_tools

[juanmanuelramallo]

What this does

The RubyLLM::Agent tools class macro accepted only positional tools and ignored the tool-call controls (choice:, calls:) that Chat#with_tools has supported since 1.13.0. The docs state "tools maps to with_tools", but passing the options either crashed or was silently dropped:

class MacroKwargAgent < RubyLLM::Agent
  tools DummyTool, choice: :required
end
MacroKwargAgent.new
# => NoMethodError: undefined method 'name' for an instance of Hash
#    (the choice: hash was swallowed into *tools and treated as a tool)

class MacroBlockAgent < RubyLLM::Agent
  tools(choice: :required) { [DummyTool.new] }
end
MacroBlockAgent.new.chat.tool_prefs[:choice]
# => nil   (silently dropped)

This PR makes tools accept choice: and calls:, store them, and forward them in apply_tools, so both the positional and block forms set the tool preferences on the underlying chat, equivalent to with_tools(*tools, choice:, calls:).

• Reader path preserved: tools with no args/options still returns the configured tool list.
• Options propagated to subclasses via inherited.
• Forwarding **{} is safe since with_tools/update_tool_options already skip nil options.

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

Required for new features

• I opened an issue before writing code and received maintainer approval
• Linked issue: #___

PRs for new features or enhancements without a prior approved issue will be closed.

Quality check

• I ran overcommit --install and all hooks pass
• I tested my changes thoroughly
  • For provider changes: Re-recorded VCR cassettes with bundle exec rake vcr:record[provider_name]
  • All tests pass: bundle exec rspec
• I updated documentation if needed
• I didn't modify auto-generated files manually (models.json, aliases.json)

AI-generated code

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

API changes

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.85%. Comparing base (978d5f2) to head (8c91247).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #806      +/-   ##
==========================================
- Coverage   88.47%   82.85%   -5.62%     
==========================================
  Files         122      122              
  Lines        5898     5903       +5     
  Branches     1405     1405              
==========================================
- Hits         5218     4891     -327     
+ Misses        680      679       -1     
- Partials        0      333     +333     

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