Add AWS Bedrock Guardrails support

[Jbrito6492]

SKNK-7473

What this does

Adds AWS Bedrock Guardrails support to the ruby_llm gem by injecting guardrail headers (X-Amzn-Bedrock-GuardrailIdentifier and X-Amzn-Bedrock-GuardrailVersion) into Bedrock API requests. Headers are applied after AWS request signing to avoid invalidating the signature.

Also includes:

• No-op cache_prompts method on Chat for compatibility with ruby_conversations gem (Bedrock does not support prompt caching)
• Gem name updated to ruby_llm_community
• Reduced log verbosity (bodies: false in connection logging)

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
  • 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)

API changes

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

New Configuration Attributes

RubyLLM.configure do |config|
  config.bedrock_guardrail_identifier = 'your-guardrail-id'
  config.bedrock_guardrail_version = '2'  # defaults to 'DRAFT'
end

Files Changed

File	Change
lib/ruby_llm/configuration.rb	Added bedrock_guardrail_identifier and bedrock_guardrail_version config attrs
lib/ruby_llm/providers/bedrock.rb	Added build_guardrail_headers method
lib/ruby_llm/providers/bedrock/chat.rb	Inject guardrail headers after signing in sync path
lib/ruby_llm/providers/bedrock/streaming/base.rb	Inject guardrail headers after signing in streaming path
lib/ruby_llm/chat.rb	No-op cache_prompts for Bedrock compatibility
lib/ruby_llm/connection.rb	Disable request body logging to reduce noise
ruby_llm.gemspec	Rename gem to ruby_llm_community

Related issues

SKNK-7473 — AWS Bedrock Guardrails integration for Lexi