feat: add config DSL methods for PII redaction (T7)

[dpaluy]

Summary

Implements T7 (#44): Config DSL methods for enabling pattern-based PII redaction.

New Config API

TraceBook.configure do |config|
  config.redact :email, :phone, :credit_card    # Enable specific patterns
  config.redact_group :api_keys                  # Enable pattern group
  config.redact_pattern(/secret=\w+/, "[SECRET]") # Custom pattern
end

Included Changes

• T2: Validators module with Luhn algorithm and SSN range validation
• T3: PATTERNS hash with 16 built-in patterns:
  • PII: email, phone, ssn
  • Financial: credit_card (with Luhn validation)
  • API Keys: openai_key, anthropic_key, aws_key, stripe_key, github_token, github_pat
  • Auth: bearer_token, basic_auth, jwt
  • Network: ipv4, ipv6
  • Crypto: private_key
• T7: Config DSL methods (redact, redact_group, redact_pattern)
• Pattern groups for batch enabling (pii, financial, api_keys, auth, network, crypto)

Validation

• Invalid pattern names raise ConfigurationError at config time
• Invalid group names raise ConfigurationError at config time

Test Plan

• 14 new config DSL tests added
• All 160 tests pass

[dpaluy]

Closing as obsolete after Tracebook v1.0.0 moved to the RubyLLM Chat/Message architecture and removed the old interaction-recorder paths this PR was based on. Current OPF redaction backend work is tracked by #68/#69.