Add Custom Reporters/Formatters

[jedau]

Description:
Create additional custom formatters (JSON, JUnit XML, Slack, etc.).

Acceptance Criteria:

• Create test/support/formatters/ directory
• Create junit-formatter.ts for CI integration
• Create slack-formatter.ts for notifications (optional)
• Create json-detailed-formatter.ts for analytics
• Document in ARCHITECTURE.md
• Add configuration examples